Are SRM plates Surflex?
I had so much slipping under power with Surflex plates (in a Tony Hayward belt kit) with a dark friction lining material, that I could not understand why other people weren’t having the same problems.
As soon as any oil, of any kind or grade, got onto the plates, they slipped like Hell.
Removing the lining material (surprisingly easy with a penknife) and gluing cork mat in its place, put a stop to all slipping. The spring adjuster nuts are now backed well off, for a light action.