83 Nighthawk 650 brake question

I just replaced my tires and decided to check my brakes while the wheels were off but cannot get the cover off of the rear drum brake. The cover spins around and will "lift" about an eighth of an inch before catching. I have tried putting opposing levers under it but no luck. What am I missing? I did spray the gap with PB Blaster tonight and will try again in the morning. The bike was kept outside before I got it but it has very little rust.

 

I could really use some help on this. If I'm not describing it tight, please let me know. I have the wheel on the bench and I thought the cover just lifted off. I don't know what could catch but it feels like there is a lip or something and I'm not sure how much pressure I can put on it.

 

that happens to old cars with drum brakes, but they had adjusters on them. yours has no adjusters like that so the pads collapse all the way.
must be something the axle goes through. if you spin the plate, does anything on the drum side move, like where the axle goes through?
can you see the bearings, do they spin independently ?

 

Make sure that the brake cam is turned so that the shoes are not expanded.

 

Thanks for the responses, it was the cam. I turned it with a vise grip and it popped right off. I didn't get the way it operates until I saw it with the cover off, now it makes sense. Thanks again.