I bought a Pioneer RT-909 reel to reel brand new around 1980. It worked for about 6 years and died.
After about 12 years I got the urge to try to bring it back to life. I did some research and found a seller on eBay that sold special kits with the new belt, pinch rollers and the bearings that disappear when you take off the cover over the belt area. The seller claimed that this kit would fix most problems with this deck.
It was not easy for me as I typically am much better at demolition as opposed to repair. I am happy to tell you that the kit was exactly what was needed. About 3 months ago I managed to fully utilize the kit and have my 909 working perfectly again.
It is my pride and joy and I have recorded from many Cd's to it. I prefer the reel to reel playback sound over a CD any day.
The deck works so well that I can't tell any sound quality difference between the 3 3/4 ips speed and the 7 1/2. As you may know you end up with a lot of music with two sides of a 3600' tape at 3 3/4 ips.
Before the 909 I owned a Pioneer 1020H reel to reel. It was nice but I don't really think it was in the same league as the 909. The 1020H did however go through a lot of tape when used at 15 ips.
Hope you enjoy the Revox.