The hot water pressure in every other faucet in the house is fine, but in the shower it's a little more than a trickle. I removed the shower head and pulled out the cartridge (it looks kind of like this).
The water was only coming out of the left hole and it was hot water. There was no cold water coming out. It's a single handle shower and if I turn it toward cold there is plenty of pressure, but then if I move it back toward hot then at a certain point it kind of jumps a little and then loses all pressure.
Best Answer
I would first check the valve's anti-scalding setting. You have to take off trim and this is usually a setting on the valve outer stem. Make sure this is set to as hot as possible. This could have slipped. Next I would check the filters inside your valve cartridge. There is usually a filter for cold and another for hot. The hot filter could be clogged and need cleaning (very seldom do these need replacing except the rings).
Lastly you might need a new cartridge or to have yours rebuilt. If you know the model this might actually be easier than all of the other troubleshooting but often isn't needed. The cartridges can cost as little as $10 and up to a couple hundred.