@jtown, you said that you changed the belt. (OEM or aftermarket) even its stated to fit for this model, sometimes belts vary in lenght and widh.
Your CVT and clutch ramps might be to smooth. Check this too.
Check your CVT and clutch nuts, really tighened?
Use new nuts every time, if not, use a few drops of thread blocker on them.
Torque CVT M12x1.25 90nm
Clutch 70-80nm