JoeThomas wrote:

I recently replaced the main works inside my toilet. The toilet had been
taking too long to refill after a flush. The new insides work no better. The
package in which they came said to turn off the water, undo the interior
valve, hold a cup over it, and turn the water back on to remove sediment. I
did that and it works. For a few flushes, and then back to 30 minute
refills.
With lots of hissing and sputtering from inside the tank.

Help?

Thanks in advance,

Joe

You don't say, but it sounds like a Fluid Master 400A.
These use a rubber disc ("seal") which acts as a pilot-operated
valve. Clever design but very sensitive to even tiny amounts
of fine particles. If your water source contains particles
(rust, corrosion, minerals) the 400A may not be a good choice.

If that sounds like you, replace it with an old-fashioned
ball-cock (float on a long arm). These will allow great
chunks of debris through without choking.

Jim