Old shower faucet cartridge won't go back on/Think somethings stripped. Help Please.
So my wife has been complaining for a while about how hard it is for her to adjust the hot and cold on the shower faucet in this rental condo we have. I removed the old shower faucet cartridge, cleaned it up a bit, and went to re-install it, however it won't screw/thread back in. It seems that the area/opening where the cartridge screws back in is stripped, so at this point I am trying to figure out what my options are. I am thinking that a new cartridge won't work because the actual area/opening where the cartridge screws in is stripped, however I thought I'd post here to try and get some help. The end of the screw on the cartridge doesn't appear to be stripped, but I've included pictures of the end of the cartridge's screw, as well as other pics (The area/opening where the cartridge screws in, the whole cartridge/sleeve that slides around the cartridge, and the old faucet handle.
So anyone have any ideas? If that area/opening where the cartridge screws in is stripped what options do I have other than replacing that entire piece? It seems that such a replacement would require removal of the walls around the faucet handle, something I really don't want to get into since this is just a rental.
Any help with this issue would be most appreciated, not only by me (Yay no more complaining by my wife!), but by my wife who currently is miserable using my meager little stand up style shower. :(