Sorry, nothing is doing the trick. Called the dealer and they say the cover merely pops off with a small screw driver - um, no it doesn’t. Called another place and they want it brought in. Another dealer says they have to take out the whole thing and send it off for about $300. Hello, it’s just a darned plastic disc.
Alrighty, called another guy and he said he’d look at it and it’d be free if there wasn’t anything to it but he might charge “a little bit” if he had to mess with it a while. Anything is better than taking it to the dealer.
Thanks for everyone’s suggestions!