So, I got 2 tubs with 2 faucet handles each...with a few issues due to aging.

1) The spare bedroom tub's handles are in better shape, but its hot water handle leaks when turned on and also never comes to a hard stop when spun around. So, it will just keep increasing the water flow when spun...until it finally shuts off at some indistinct point...and then slowly increases flow again if you keep turning it.

2) In the master bathtub, both handles are acrylic Valley II handles. The hot water handle just broke off, and it also never came to a hard stop when spun around. Also, the screws holding the handles on are completely rusted away in both handles.


So my questions are...

A) I was just going to simply replace both handles in the master bathtub, but how would I remove the rusted screw remains stuck in the cartridges to insert the new screws just to do even that?

B) My other option is to just replace the whole kits for each handle, and hopefully fix the other issues too.
If I do this, would it fix the leaking and lack of a hard stop on the hot water handle?
And would I even have to remove the rusted screw stud left in the old cartridge...or could I just leave them in there since I'd be taking each entire cartridge out anyways?
And what special tools would I need to do this? Would I need to replace the seat with a seat wrench?
And would there be any possible metal-to-metal interfaces in there that could be rusted together that I couldn't get out (given the screws were completely rusted out)?

 

You can sometimes get a broken screw out but usually it's easier to replace the whole stem. Your lack of a hard stop was probably the handle spinning on the stem so a new handle should take care of that. If the seats in your valve body are in good condition you won't need to replace them.