Those 10" reels probably have sticky tape on them. Do clean the tape path components as the tape probably left gunk on them. I have not adjusted the tape lifters on a 5050 recently enough to remember how, but I imagine it can be done without too much hassle.
Installing the tape path mod kit will not solve the issues you are having. It is not intended to compensate for bad tape or to replace maintenance procedures. It is designed to reduce scrape flutter. I suggest getting the stock deck tuned up first, then adding the tape path mod.