Hi
Three weeks seems a very short time to clog. When I had these problems
I managed to remove the clog by injecting ink cleaning liquid
(solvent) through the ink input. You will find it appears jammed but
repeatedly and carefully trying with a syringe slowly starts to flow
after a while and you are there (the air compresses slightly and
that's the way to get solvent inside). Do not apply too much pressure,
you can break the piezo elements, after several attempts let it sit
for a while now and then so it can penetrate and break the clog. That
way no head dissassembly is requiered. I got some Epsons back in
business with this method.

Epsons (especially old) are reliable but when used with proper inks.
Some low quality inks tend to clog frequently and irreversibly while
others never cause trouble. When there is a partial clog, using good
ink will fix that in a day or so (no amount of cleaning cycles with a
bad ink will do). I guess good ink has some kind of solvent.

I had problems with third party cartridges when I tried a refill kit
sold at Aldi (branded Zolid). On Epsons it is easy to refill a
cartridge and I never had a clog with that ink, even when unused for
months. In my experience the ink really makes a difference.