The first thing a person should do if they notice a reduction in print
quality (white lines or gaps) is to do a nozzle check. This can be found
under Printer Utilities. This will show you exactly how many nozzles are not
firing, and give you a baseline to check for improvement. Next you should
try several cleaning cycles; many times this may get things flowing again.

There are 2 reasons for a print head to not give you a perfect nozzle check.
The first being an actual clog, and the second being air bubbles, either in
the cartridge or the print head. An old cartridge can lead to ink
"thickening" and also cause problems. Of course, an empty cartridge will
also cause trouble! If you are refilling cartridges and putting less than 7
cc's of ink in an empty chamber, you are not getting a "factory full"
refill. This will cause the ink counter to say you still have ink when it's
long gone. (See my earlier post on "The Ultimate Refill" method to see how
to get "full" refills.
OK, let's say you know you have ink, and you've done 4-5 cleaning cycles and
still get a bad nozzle check pattern.

Step 1:
Distilled water injection into cartridge
The first thing to do is try to get rid of an air bubbles. To do this I like
to inject 1-2 cc's of distilled water into the colour chamber that is giving
the bad nozzle check. To do this you will need a syringe and small needle
(available at your local vet, or farm supply). Put the print head into the
"change cartridge" position and remove the cartridge. Draw 1-2 cc's of
distilled water into the syringe and poke the needle into the rear hole on
the top of the cartridge. Aim for the middle of the bottom of the cartridge,
about 1-1/4" in. (GENTLY...You don't want to pierce the internal filter
screen). Now inject the distilled water above where the outlet port would
be. Re-install the cartridge and let the printer do its "new cartridge
bogie". Now LET IT SIT for 15-20 minutes! Then run a cleaning cycle and
then another nozzle check. Sometimes this is all it takes. The distilled
water will also help to thin ink that has become too viscous. I have run
tests with ink diluted with as much as 50% distilled water and could hardly
tell the difference, (ink ex tender?? :-). You may need to run a couple
cleaning cycles to get everything flowing again. If this doesn't work, roll
up
your sleeves and proceed to STEP 2.

Step 2:
Distilled water injection into print head
Still clogged? Don't despair. Put the print head back into "cartridge
change" position and remove the offending cartridge. Remove the needle from
the syringe and draw 1cc of distilled water. Do you see the little pointed
nipple that is in the hole where you pulled the cartridge from? This is the
post that breaks the seal of a fresh cartridge and feeds ink to the print
head. Place the plastic tip of the syringe firmly over the post.
(Gently...if you break the post you're screwed). Slowly inject the distilled
water into the post and remove syringe. Hopefully you just injected the
distilled water into the print head, where it will displace any air bubbles
and dissolve dried up ink deposits (kind a like fuel injector cleaner on a
car). Let the printer sit for a good couple hours after this. The distilled
water needs time to work its magic. Then reinstall cartridge and test as
above. If you STILL have a problem after several cleaning cycles, it's time
to get serious and remove the print head completely (STEP 3). This is not
for the faint of heart and is reserved for more "technically inclined" users
(it's really not that bad...I can have it out in 2-3 minutes). It may help
to take a photo or video "before" shot to help you put it back together
right!
Step 3:
Removal and cleaning of print head
1: Move print head to "change cartridge" position and remove cartridges.
2: LEAVE POWER SWITCH ON AND UNPLUG PRINTER CORD. This will keep the print
head where we want it.
3: Remove top cover of printer (4 screws.2 in front, 2 in back).
4: Carefully remove ribbon cable going into top of print head assembly.
5: Remove screw holding the metal arm at the bottom of the cartridge holder,
remove metal arm.
6: There is a small plastic tab in front of where the ribbon cable plugs in;
this is all that is left holding the print head.
7: Lift the tab over the protrusion of the print head and slide the print
head assembly forward and up to remove.

Scary, huh? It's easier than it sounds. Now that you have that bugger out,
it's time for a serious distilled water soak. Put enough distilled water
into a cup to cover the whole thing (don't worry, it won't hurt anything).
Now let it sit overnight. The distilled water will work its way in and do
wonders while you sleep. The next morning, rinse the assembly with clean
distilled water, shake off excess and let dry. Now we're ready for the real
"nozzle test"! Get a foot of small bore plastic tubing that will fit onto
the plastic tip of the syringe. I use a 1/16" I.D. tube that I soften with a
lighter and widen the opening with a Bic pen so that it will slip onto the
syringe. Now draw in 5-6 cc's of distilled water through the tubing into the
syringe. Place the open end of the tubing over the feed post of the clogged
colour. Now firmly inject the distilled water. If the head is clear, you
will see 32 (colour) or 64 (black) very, very fine streams of distilled
water spraying out of the nozzle plate on the bottom of the print head. If
some are crooked or not spraying, we need to back flush that colour. VERY
GENTLY clamp the print head (bottom side-nozzle plate- up) into a small vice
or holding fixture of some kind. You will need both hands free. Now take
your distilled water -syringe-tube combo and hold the tubing firmly over the
micro-sized nozzle holes on the nozzle plate (a magnifying glass will help).
While holding the tube firmly in place,
force some distilled water into the nozzle holes (you know it's going in if
it drips out the feed post). Keep moving and repeat until you go over ALL
the nozzle holes. What this is doing is back flushing each jet in the print
head and dislodging any foreign objects (dust, etc...) out of the print
head. If a head has a rock in the pipes (dust, etc...) and you only flush
from the top...you're just pushing it to the spray nozzle and
it's still going to be clogged. A back flush like this is the only way to
clear this type of clog, unless you replace the print head. Now you can slap
it back together, run a couple cleaning cycles, and get back to printing.

I have not met a clog that I couldn't clear with the above methods. I
recently had a 500 in the shop that someone had let the black run bone dry.
4 WEEKS LATER, they installed a new cartridge and ......"chaaaaaa.....know
what???? unh-unh!!!" Clog city. No amount of cleaning cycles or distilled
water injection would clear that gooey up print head. EVERY SINGLE NOZZLE
WAS CLOGGED. This was a candidate for the old Epson "replace the print head"
routine. So I figured what the hell! Let's pull the print head and test the
"procedure". After a "Step 3" full boogie removal and back flush, I ran ONE
cleaning cycle and......PERFECT.
Remember, this head was so clogged that I couldn't get even 1 nozzle to
spray! I know it's kind of involved, but for us techies out there or for a
printer out of warranty......it's the only way to go. Feel free to post
questions to the Epson-Inkjet list or e-mail me direct. Good Luck!

Addendum:
Added by Jim Liddil on the Epson-Inkjet list.
For just such an occurrence keep a clean empty cartridge on hand. Fill it
with distilled water. Use a syringe and make sure it is full. Easy to do
since you won't get ink everywhere. Put this cartridge in place of the other
one. Let is sit and run cleaning cycles. You can let it go overnight if you
have patience. If this fails then you can try the approach of putting a
piece of tubing on a syringe that is just big enough to fit snug on the post
where the cartridge plugs in. Then GENTLY try to force water or 70%
isopropyl alcohol through the head. Put the water cartridge back in and run
cleaning cycles. If all this fails it's time to send it to Epson or pull the
heads yourself and clean them. My techniques are slight modifications of
those presented by Steve Chlupsa.