Torque it up a little tighter is a good idea. I also sometimes use a washer made of a piece of drywall sanding material. It looks like screen wire with abrasive on it. I cut a piece that is twice as big as what I need and fold it over. That way it is doubled and I cut a small hole in the center to go over the crankshaft. It is thin enough that it does not take up enough space to matter. One piece would make dozens of washers. I normally use it between the back plate and prop.