On my Moen shower facet

It sounds like you know what you're doing, but if it has O'rings, try replacing those. If there is a snug fix with the valve then the leak is a problem with the inner workings of the cartridge.

Moen makes a stem removal tool that angages the 2 ears on the outer portion of the stem. You can order from Moen:
http://www.moen.com/moen/cartridge-removal-tool-for-1200-or-1225-or-1222-cartridges/_/R-COMMERCIAL%3A104421

Or your local home center or hardware store should have one in stock if they carry Moen parts.

This is a very simple fix. NOTE: This is for a Posi-temp model only!! First turn off the house water. Relieve the water pressure at a nearby sink. Then remove the handle from the faucet. Remove the black plastic piece, then the two white plastic pieces (these control how hot the water gets by controlling how far the handle turns), then the metal cover over the center piece of the valve. Once these are out of the way, there is a small metal clip that you can see that holds the cartridge in place sitting in a **** on the top of the center piece. Remove this carefully with a small straight edge screwdriver, taking care not to lose it. Then with a small pair of pliers, pulling on the center of the cartridge, pull straight out. Once the cartridge is completely out, turn it counter clock wise, 180 degrees and then reverse the process. The hot/cold will be in proper location now.
Now for an older style, simply take the handle off, turn the center portion of the cartridge 180 degrees counter clock wise and return the handle. Hot/cold will now be in their proper locations.
Good luck.

you may have deposit's,(mineral) in water way's. maybe piece of cartridge came off and blocking water. try removing cart' and inspect brass valve body,to see if any thing is there. check cartridge as well.

Once you have removed the U shaped cotter pin whis is brass in colour. Use a pair of plyers and hold on to the brass stem. you will need to pull fairly hard to remove. If you have the white or black stem loosening knob which comes with the replacement cartridge you can insert that into the brass cartridge where the plastic sides of the cartridge are showing. Turn your plastic konb clockwise to loosen the cartridge and then pull out.

You are not the first. Usually you must break the plastic handle to remove it and then you can access the screw and have leverage to hold the brass stem with pliers while you try removing the screw. Caution, do not try to bend the handle to break it off or you will break the brass facet stem. Also, there are two styles of handles: one has a short innercone,the other has a longer inner cone. You need to know this before you purchase a replacement. Goodluck< Macgivor

If you are talking about the black rubber sleeve that is around the outside of the cartridge, you will have to CAREFULLY work it out with a flat scredriver. Be careful not to dig into the brass housing of the rough-in valve. It may be a little painstaking, but this will work. I have also used a piece of copper pipe to work on that rubber piece. The copper pipe will not dig into the brass the way a screwdriver will. May want to try that first.

A stem is a cartridge in a real old valve. You have pulled retainer clip, you can try to pull it out with pliers, but you might need a moen cartrigde puller.

It sounds most likely to be a bad cartridge.

Hope this helps

hi carey. turning the cartridge upside down will not change the direction. But tell me this, once you get used to the new cartridge won't it be fine as it is?