fiery,
Next time you need to pull the backplate from a PAW , go to your hardware store with the engine and look through the "mudgard washers" - may also be called "gutter washers" these are larger outside dia than regular washers of the same bore/bolt fitting . I have a selection of sizes myself and never fail to find 1 that fits into the PAW slots, just grip the washer in a vice , hold the emgine with the backplate fitted to the washer and twist.
Stewart