I'd recommend a diagnostic check to see if any fault codes flag up.
What condition is the battery? As low electrical power can cause various issues.
Could still be the servo.
5 years or 120k whichever comes first I think for Cambelt. Definitely make sure service history is good. And oil changes for gearbox and quattro system. Check out buyers guides on YouTube
I did it for peace of mind. Regular oil changes/flushes etc.
I was doing minimum once a year. More if I were doing road trips.
Got to get my engine rebuilt now.