Moen faucet with a plastic handle. Handle has broken two times. Does not turn easily. Once handle slips few times it will break inside the cap leaving you unable to turn the water off.

single cartridge? pull old one, flush some water through empty valve then install new cartridge. once installed, make sure the horseshoe clip is properly inserted to keep the stem in. once the clip is in right, there is a chrome tube with a ridge that slides over the barrel and the clip. the ridge acts as the stop for the handle. also make sure there are stops inside back of handle to hit the ridge on the chrome tube. the plastic inside the handle may break off allowing the handle to spin. the stem unit/cart may also be installed 180 degrees out of place. pull the lock clip and use the remover tool that came with new cart to rotate it 180 degrees with water supply turned off.

1st put the DOME cap on by rotating it 180 degrees, to go OVER the white plastic gasket, then press on. Then you have to get that plastic square knob inside the dome, in a downward postition, thus TURNING the WATER ON, to work the handle back in place. Put the set screw on with an (tiny) allen stick wrenchy thingy.

Call plummer to have it replaced

The exact procedure to remove the old cartridge is with a plastic removal tool.With replacement cartridge you have to buy this plastic removal tool.Also there is same metal removal tool available.With the help of this tool you can easily remove the old cartridge.
Moen Cartridge Replacement Instructions

Moen shower faucet cartridge replacement is a project that will take some time to get done right. When is it time to replace a Moen cartridge? If you are like most people, you won't want to replace your old Moen cartridge until your old cartridge is starting to show its age.

Replacement is necessary, usually, once the old faucet starts to drip. Thankfully Moen faucet cartridge replacement is not difficult. However, if you are uncomfortable with doing the repair yourself, do not hesitate to call a professional plumber to do the job for you. This will guarantee that the job is done right.

If you follow these Moen faucet cartridge replacement instructions you will be able to replace your old cartridge by yourself. First of all, as with any plumbing repair, make sure that the water supply is turned off. Open the faucet to remove water pressure from the lines and let the remaining water drain from the pipes. You will then need to remove the faucet's handle by removing the decorative cover and removing the retaining screw. This will allow you to remove the handle.

Once the handle has been removed, work on releasing the splash plate from the wall. Generally there will be one or two screws to remove and the plate should release from the wall easily. From here the process begins to get a little trickier. Insert a shower stem socket onto the faucet valve's retaining nut and release the nut. Your Moen cartridge removal will be complete once you grab the cartridge with a pair of pliers and pull straight out to remove the old cartridge.

Clean any surfaces that you have access to and replace with the new cartridge. Follow all of the previous instructions in reverse order to re-assemble your shower faucet. Check to make sure that all the connections are tight before turning the water back on and testing the system out.
Now in your case the broken/cracked while removing the old cartridge so try this procedure carefully to get the stuck -up old cartridge out.
TAPPING the Threads into the Cartridge:
Carefully  hold one tab on the cartridge tight against the brass lip on the faucet body with needle nose and try  to drive the 1/2" tap into the smaller bore of the cartridge. It will take  about 15 minutes to slowly work the tap in all the way (maybe 3 turns?). Then  back out the tap... remove needle nose. [remember to turn the tap 1/4 turn back, for each 1/2 turn forward ... this clears the metal particles from the tap and makes the next 1/2 turn forward go smoother].

Next, assemble a 1/2" x 4" threaded rod, so it had threads all the way to the two jam nuts on one end)... If you use a bolt, get one with threads all the way up to the head. you may find it hard to find - so try a carriage bolt and spin a nut all the way up to the head .... continue: 

next on the bolt goes a 1/2 nut (this is the "jacking nut") and a flat washer so the jacking nut can spin easily against the next piece, a 1/2 drive socket (7/8" ) with the square hole toward the washer and jam nuts ( bolt head ).
The open end of the socket faces the brass body of faucet and rests on the round brass lip... having the same inside diameter. This allows a space for the cartridge to be pulled into ( a cavity). Thread the bolt into the tapped cartridge and snug it up so the 7/8" socket is aligned with and resting against the brass body. If the cartridge spins smooth, the threaded rod is GREAT. You can just work with the 1/2" rod and use needle nose (or similar) to stop the  cartridge from spinning, to get the rod threaded into the tapped threads in the cartridge... then, slip on the socket, washer and nuts.

Now snug it up tighter. Check socket alignment. Then begin turning the jacking nut ( the "extra" nut) until it contacts the flat washer and 7/8" socket. Now, as you continue to tighten the jacking nut, it will pull the 1/2 bolt (threaded rod) away from the faucet... and the cartridge will come along too. [You have to prevent the 1/2 rod from spinning while tightening the jacking nut. put a wrench on the bolt head.]
This procedure is bit lengthy and requires some appropriate tools,but this will release the stuck cartridge out.
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Take handle off and check out the inside to make sure it not striped out and on the top of the handle it may have a plastic cap to pop of to access the screw holding in in place you amy have to use a knive to get it off .

If you can't see a set screw it may have a screw in handle on top.

There is a little cap on the top of the handle, after removing in there is a philips screw under that and that will release the broken plastic part.

It is a plastic cartridge the only way I have gotten them off is by turning until cartridge stem breaks it will not hurt faucet

You can try to rotate the first plastic ring to the left of center a few teeth, this will let the handle advance alittle more to the hot side.

Moen single handle - push pull has a screw beneath the handle cover plate. The Moen single lever handle has an allen wrench screw located under the curve of the handle. Once either one of these screws are removed, the handle should come off easily.
Once the handle is off, the water must be turned off and then you can remove the cartridge. Some cartridges are difficult to remove and may require a special tool. Most new cartridge packages have information on them to explain how to remove the cartridge.

Hi varn4620,

I'm Harvey the Master Plumber.

Your question is: You had to replace the faucet in the tub due to a broken plastic piece in valve stem. Bought a Moen ripped the wall out and put new faucet in. Went good untill we turned the water on and the shower rained on us. Tightened everything you could find to tighten .Every time the water is turned on the shower rains. Can this be fixed or is the faucet broken?

Is this new faudet a single handle? If so I"ve had this experience also. Most of the time it's because the guts were not lined up properly at the factory. You may have to play with it a bit.
Turn off the water and take the handle off and remove the sleave, remove and rotate the guts. Try 90' at a time. Turn water on to try it. Useually one of the other 3 positions will be right. The correct position is there, but it may take time to find it.

Feel free contact me again!
Please give me a rating here at fixya before you sign off
Thank you,
Harvey your Master Plumber