The only reason I've been thinking it's not that is that usually, if the front sprocket even starts jumping splines, the bike stops moving at all pdq! :yikes:
Belts that are 'loose, but still engaging teeth' do tend to at least provide some drive, and usually, only slip on acceleration! So I was trying to be hopeful for derby.... :dontknow:
Still, it's always hard diagnosing things like this over the internet/without actually seeing it in person, isn't it!? Even with video's &/or sound recordings, it's never quite the same as being there and actually looking at it/listening to it in person! :banghead: