Omio X8-2200L-USB problem - fix, rebuild or sell

I have used a Omio X8-2200L-USB for 2-3 years and since day one there have been problem, it "oversteps" sometimes - it occurs in a few percent of the runs so it's hard to fault seek. Typical some mm in Z but sometimes also in X. I have contacted support, not much help there.

I recon it's related to drivers and/or steppers. G-code is OK, I have tried several different computers. So there is three options:

- Try to fix this - if it's possible.
- Rebuild it completelly with new electronics and motors.
- Sell it and buy a new one.

Thoughts on this?