[Amps] Auto tune conversion using stepper motors?

[Markku Oksanen]

All
I have a home brew GU-84b amp that I don't seem to be able to sell so perhaps I keep it and upgrade a bit.
The question is: Do stepping motors, properly used, big enough, etc. keep their position information accurate so that they can be used to tune the amp?  I already have the band switching done with the B1B and B2B Russian RF relays and both the tuning caps are vacuum so stepper motor step size will not kill the idea.  The conversion gets a lot more complicated if I need position feedback such as potentiometer.  I was just thinking perhaps at every power up running the caps to the limit with current sensing on the motors so that the limit is detected (or is it?).   What is the proper way to do this?  
I was searching the net for multi-turn (more than 10) hobby servos but didn't find any.  Naturally a proper pair of servos would solve this nicely.
Thanks!
MarkkuOH2RA/OG2A/WW1C