I have a 55w CO2 machine, but also at the beginning had some issues with the setup
A couple of tips that helped me were:
Changing Line Interval from 0.1mm to 0.05mm (more coverage)
Using masking tape in the other side of the tumbler, for a better grip (avoid slippage)
Use IPA for cleaning
I’ll try that for slippage but I just ordered the new rotary. Mine is fine for flat ones but when I get curved cups, it turns into a challenge. I bounced back and forth from 0.05mm to 0.1 and found the best results on mine is at 0.1. I also started using acetone for cleaning, what a huge difference. Initially I was using soap and a magic eraser which did well but it took too long.