I just bought a broken 2017 RZR 170 . It does not go forward but does go backwards. It feels like it takes a lot of throttle to go backwards but I never used one that worked to know how it should feel.
It seems to run great. The sellers thought it may be a bad gear in the transmission or something.
I have not looked at it at all. I just brought it home. I figured I would get a jump on troubleshooting by asking here ahead of time.

Utah RZR Rentals