This fellow tried the sandpaper trick. Of course made for an inexpensive engine for me after I find a new thrust washer.

The more you clamp down on a plastic backplate the more its going to deform and that is going to cause problems even out of round running. Many all plastic spinners do not have backplate capture rings and now When you really crank on the torque they become explosive.

Suggest if you use plastic at least get an aluminum backplate type and with a capture ring such as the CB and Associates sold by RJL or there is one Great planes type with alum backplate and capture ring.