I just had to retile the bath surround on our hall tub/shower due to my not maintaining the tile grout. OK, so I think I'm just about done with this job, and try to put the tub faucet back together. Oh-oh. The little handle won't go back into the valve! In the attached photo, the red arrow shows where the handle is supposed to fit. But apparently in the place it's supposed to screw into, the outside housing got shifted a little, because the handle won't fit in the hole any more. If you look closely, it looks like the hole in the outside housing (I don't know what that thing is called, the part with the hole the red arrow points to) is shifted slightly.
So, I have tried twisting and (gently) tapping the housing with a hammer, but no luck. When I was taking it apart in the first place, I tried to get this housing off, but it wouldn't come off.
So I am wondering:
(a) Is there some way to get that thing off (hidden cotter pin or something)
(b) Can you just replace this thing? The house is 13 years old, so if I had to replace it, it would not be a big deal. Do I need access to the tubing from the back, or are these valves drop-in replaceable?