Dawn wrote:

I am trying to replace the the works in my toilet tank using the
Fluidmaster 404LG repair kit. Everything was going great. Then I
got to the point where you flush water through the uncapped fill
valve and check for leaks. All went fine, no leaks and water was
definitely flowing through the fill value and into the bowl. So, I
turned off the water and placed the valve cap assembly back on the
fill valve and locked it into position by turning it clockwise an
eighth of a turn. I turned the water back on, but it was stopped at
the fill valve--when the cap is on the fill valve it does not let any
water flow into the tank. So, something is wrong with how I put the
cap back on, or perhaps I jostled some part of the valve? I have
tried and re-tried several times and can not get water to come out of
the capped valve. Before I call a plumber, does anyone have any
advice?

There are some YouTube videos about Fluidmaster valves.

When you remove the cap and turn on the water valve, there should be a
strong stream of water out of the Fluidmaster body (keep hand over it
so it won't spray the ceiling). If not, the water line is clogged,
maybe by the rubber seal at the bottom of the toilet tank where it
goes into the Fluidmaster body. Also when you manually move the arm
with the cap removed, do you see the stainless steel pin move in and
out the tiny hole in the middle of the rubber plug?

It's going to be cheaper to buy a second Fluidmaster valve than to
call a plumber.