Moen has been in the business of manufacturing faucets since 1947, and the bulk of them are of the single-handle cartridge variety because Al Moen was the inventor of this type of faucet. Like all manufacturers, Moen makes mistakes, and one of them was to fashion the set screws for their lever-style faucets from a soft metal that gets easily stripped. If you put too much force on the screw to tighten it down when installing the faucet handle, and you strip it, you'll have a problem when it's time to remove the handle for repairs.
A stripped screw head is bad enough, but the screw itself is inset — and it's tiny. It's difficult to get any tool other than the 7/64-inch hex wrench that Moen recommends into the hole. Most people don't even own a 7/64-inch hex wrench and will use an 1/8-inch one instead. But if you do that when installing the handle, you could possibly strip the head even more.
A Stuck Moen Shower Handle Set Screw Is Common
If you're confronted with a stuck set screw in the shower faucet handle or a stuck Moen kitchen faucet set screw, you're not alone. Homeowners have sought advice for this problem in several internet forums and have received a number of helpful tips.
A common piece of advice says to use a drill and an 1/8-inch drill bit. You set the drill in reverse and keep downward pressure on the screw while running the drill at low speed.
Another common tip suggests loosening the hex nut with a torx screwdriver. A T-25 torx driver has the same number of points and is the same size as an 1/8-inch hex wrench. If you can get the driver straight into the hole, you should be able to wedge it tightly enough to turn the screw.
The problem with both of these approaches is that wiggle room under the lever is limited, and it's difficult to get a drill bit or screwdriver to go straight into the hole. If the bit or screwdriver contacts the screw at an angle, they can potentially strip the head even more.
Using Glue to Remove a Screwless Faucet Handle
No faucet handle is really screwless, but some have screws you can't see, and that's the case with Moen lever-style handles. The reason you can't see the screw is that it's hidden under the lever, and that's why conventional strategies for removing stuck screws don't work. You need a hex wrench because it's bent into a 90-degree shape that fits.
This fact leads to the possibility of gluing the hex wrench to the screw with super glue or epoxy, but there's a good reason why you don't want to do this. The glue will bind the screw in the hole, and removal will be impossible. This suggestion is on the right track, though.
Use valve grinding compound, also known as valve lapping compound, instead of glue. Valve grinding compound comes in small tubes, it's inexpensive, and it's available at most car parts stores.
Removing a Stuck Set Screw with Lapping Compound
Lapping compound is an abrasive. Although it does stiffen, it doesn't set completely like glue, and it won't bind the screw permanently.
To remove a Moen kitchen faucet set screw or shower handle set screw, first coat the end of an 1/8-inch hex wrench with a generous amount of lapping compound. Insert the wrench into the screw head and push down. You might want to wait for an hour to allow the compound to stiffen.
Push down on the bend in the wrench while simultaneously turning the end counterclockwise. Give the end of the wrench a hard jerk to dislodge the screw. Keep downward pressure on the wrench when the screw starts turning and release pressure gradually as the screw gets easier to turn.