I recently discovered on YouTube that you actually locate two tabs on that shim that goes between the base and the motor, onto the motor before you place it down on the deck, ready to bolt it on.
Before learning this step, I would just place it onto the deck and bolt the motor on top.
Two of my mowers have been done this way and I have probably deformed the locating tabs.
I understand the purpose of the shim is to shield the magnetron from dust ingress. Have I likely compromised effective debris sealing and should I take them apart to do them the right way?