After a bit of online searching through appliance repair forums and consulting with the folks at Appliance Parts Pros, it seemed that the culprit was the oven door hinges. I ordered replacement ones, installed them, which took care of the problem. Unfortunately, tenants (this is for a vacation rental home) are quite a bit rougher on stuff than we are, so I've had to replace them multiple times. At least I now know how to do it, and have it down to about 20 minutes! Hope this doesn't become a regular competition...