Pam111 bad.
Servicing a 7750 is something that takes a lot of time. There are many things that can go awry when messing with them. I rarely work on them unless it is my own piece. In many cases where I am dealing with a 7750 that has totally seized up, a complete disassembly usually uncovers so many severe problems that it is almost better to replace the movement. If you get it servicd starting on day one and maintain it, you should get a pretty good lifespan.