I have a 21 600T with 850 miles. Still has the original belt. Put in a MSC stage 1 kit last year when it had around 500 miles.
It's been a while since I ran the machine, but recently a family member attempted to reverse it off my trailer while the right rear wheel was still strapped to the e-track chock (strap over wheel style). The machine was in 4wd at the time and it obviously couldn't move. I'm not sure how much throttle was given until it was realized. You normally have to give it a bit of gas to get it over the bump of the chock so I'm assuming it was that, plus some (a good amount overall).

I took it for a ride today and when you give it just enough throttle to move, and hold the throttle in that same position, it starts to move and then cuts out and then picks up again but only after more throttle is given. Very jerky. Like the clutch engages, then disengages. Once you accelerate or hold a steady throttle at a higher speed, it seems fine. I may just be paranoid since the trailer incident, but I feel like I would have noticed if this was happening before. What damage could have been caused, if any? I worry about the belt and/ or the differential. No idea how these gearboxes are set up. What happens if one wheel is locked up while in 4 wheel drive and throttle is given? I haven't taken the belt cover off yet, wanted to get an opinion here first.

[2015 Z Force 800 53/Trail EPS]

Do take the belt cover off and inspect the belt...every inch as closing the primary on a belt that can't move burns the entire area that was contacted by the sheaves. It may only look glazed in that area.. but it may also be narrower from wear in that area so measure and oddity as well.

Thanks, sort of figured it was going to be that... Will open it up tomorrow. Any suggestions on an aftermarket belt? OEM is $230 and probably not of any better quality. Ultimax OK?

[2015 Z Force 800 53/Trail EPS]

Thanks, sort of figured it was going to be that... Will open it up tomorrow. Any suggestions on an aftermarket belt? OEM is $230 and probably not of any better quality. Ultimax OK?

Well when mine needs a new one it will be the Ultimax