Here’s a thread on replacing encoders. The last post contains a video of the process, and a method for restoring encoder performance without replacing the part itself. Very odd that they’re only broken in MIDI mode though, not heard of that happening before.
Also not heard of anyone replacing buttons on OT, but it apparently isn’t too difficult on monomachine.
Support is the way to go, i’m sure they’ll give you options, and advice on doing it yourself if that’s possible and what you choose to do.