SANYO EM-D9550 Turntable problem

We have a Sanyo EM-D9550 combination microwave oven which is about ten years old. It has been very reliable except for two small problems.

Some time ago, the ring under the turntable with wheels on broke. Unfortunately (yes, stupid I know), it was used a few times before the wheel was replaced. Now the turntable doesn’t turn at all. Everything else seems to work. If I remove the turntable, the thing in the middle that the turntable would sit on is very loose and can be lifted up a bit. As it was some time ago, I can’t guarantee what has or hasn’t been done to this thing after it stopped working.

My question is: Is this something that is likely to be reasonably inexpensive to have fixed? Or is it something that would cost so much that it would be better just to put up with the turntable not turning (as we’ve been doing) or buy another combi? I’ve read online that the belt could have come off, but wonder if it is more than that.

I am aware that microwaves are very dangerous appliances to service, and have no intention to do anything to it myself.

Secondly, the door has a crack at the top near the hinge. It’s not causing us any problem that we’re aware of, but should the microwave be leak tested? The door appears to close properly and tightly.

Any advice?