[Diana]

Make sure the track is clean (snails, moss, riccia are the most common things I find), and the filter is pumping water very well. If the filter slows down the water trickles under the biowheel without making it turn.

 

[Diana]

Twisting the paper makes the distance from end to end a tiny bit less. If the wheel was binding at each end, so not running well, this will help, until the paper relaxes. Also makes the diameter of the paper part a tiny bit smaller. Not sure how this helps.