I decided to clean the centrifugal oil filter before trying to start the CB160. When I opened it up, I found that both tabs on the cover had been broken off. I tried tapping around the edge, and I can see movement, but it never moves enough to get a hold on the edge to pull it out. I've also tried turning the cover by tapping with a chisel against the remains of the tabs. So far, that cover doesn't want to come loose. Any ideas out there?