I have a single handle Price Pfister Avante single handle valve in a shower. The handle turns right/left to adjust temperature and moves in/out to adjust the flow. The handle can be moved about 1/2 inch in and out of the fixture. This shower was rarely used but worked in the past. Recently I discovered that there was very low flow from the shower head, even with the shower head removed. The max flow is probably about 1 cup a minute. This valve has another output consisting of a capped pipe nipple coming out of the wall below the valve. (I have no idea why this is there.) I tried moving that cap from the lower to the upper outlet, but the flow was same from the lower output. I've tried blowing compressed air into both outputs with the cartridge removed and also tried replacing the cartridge. Nothing I've tried helps. If I remove the cartridge and turn water on to the house, tons of water comes out of the valve body, so there doesn't seem to be a water supply issue. Any one have any ideas?