If you are on the east coast another great person is Ryan at reel to reel tech.
He is wealth of info on open reel decks and tape.
https://reeltoreelhaven.com/collections/decks
On a 5050 BII, the two first steps should be to pop the head block off and send to JRF.
2. remove the pinch roller and send to terrysrubberrollers.com and get a fresh tire.
As davidchampa noted, the labor to go through a deck is not going to be inexpensive. I have gone through 4 5050s. Some needed a complete recap others really only needed the pots cleaned. The other area to look for are the relays which usually either have to be cleaned or replaced. The 5050 machines are so well built once you go through them, I can't imagine anyone wearing them out in home use.