The motors and the capstan should be oiled. Any high-quality machine oil will do.
Small amounts of corrosion on the heads, guides and rollers can be scraped off with a lemonwood stick. I scrape and clean, scrape and clean. Usually many cycles of this are needed.
As a solvent to clean things, I normally use ethynol. If it's a little more stubborn I use acetone (but it will damage most plastics, so watch out.) If it's REALLY stubborn, I use toluene (also harmful to plastics.) Always work in a well-ventilated room. Toluene is the most dangerous of the solvents.
You can polish the aluminum rollers if you wish, but be sure to clean extra well afterwards to remove any micro aluminum particulates.
If you polish steel parts, they will need to be demagnetized afterwards, as the polishing action slightly magnetizes them.
Idler bearings should be CLEANED and then RELUBED. A heavy (high-viscosity) machine oil is recommended.
Best,
Fred Longworth