Have a 3 knob shower/tub set up in the bathroom of my parents vacation home American Standard that was installed probably around '71 Need to replace the diverter stem but the water here is very, very hard and the deposits have grabbed a hold of this thing like there is no tomorrow Now this isn't a valve stem like most I've seen on the web. These are a pure cylinder with a locking nut that attaches to the outside unlike the "newer" stems that have the cylinder and nut as one unit. On those newer types, a socket can be used to turn/force the unit to some degree The ones I'm dealing with can only be pulled straight out. If anyone cares to look, mine are Model #: 723-0038 Of course, these fit snugly to begin with so there is next to no room between the stem and the housing I've been alternating soakings with vinegar and CLR to absolutely no avail. Because the clearance is next to nothing, all I'm really doing is spraying the outside if the cylinder. Maybe a tiny bit might get along the sidewall of the stem, but very little, if any, and no depth and there's 3" of valve stem buried within the housing. I've tried wiggling with a vice grip just to create a slight "crack" in the deposits so the CLR or vinegar can begin to creep in there... No good. I'm also tapping with a hammer slightly trying to create some kind of crack or fissure or something in the deposits holding this thing fast... I don't want to use anything like muriatic acid because it scares me And would ruin the finish of the fixtures and fittings The knob itself is held onto the valve with a 10-24 screw. So I picked up a longer 10-24 screw, some fender washers and nuts along with a 10" piece of flat iron. Drilled a hole into the flat iron and screwed this like a "handle" onto the stem where the knob would go. Kind of looks like a propeller with this attached Pulled as hard as I possibly could while inside the tub with legs against the wall of the tub... Just like a rowing machine. Absolutely nothing... Except the bar was beginning to bend. I can access from behind the tub wall but that would mean removal of drywall, the sink and, even then, I'd only be looking at the copper inlet piping. I'd rather not have to go this route as I would have to cut out the inlet piping and basically replumb the entire unit. If this is my only alternative, then the whole system gets yanked and I'm putting in a single stem system but I don't have the tools for this now and would place the shower out of order until I could return... At least a month from now or more. If I could figure out how to post pictures here, I have some that might help this make more sense as I'm sure this in not reading as well as I'd like Anyone ever run into a situation like this before and figure out a way to resolve? Anyone have any ideas that might help me get this darned thing out?