I've seen several posts about when the roof won't go down--but I have the opposite problem. When cranking the roof up it goes up about a foot with the normal ratcheting clicks, then starts getting a lot of resistance on the crank handle and makes a loud popping noise with a jolt, followed by a couple ratchet clicks, then resistance and popping. It doesn't go up when it pops--just stays in place, like something is slipping, and it get's harder the more I crank it, and seems like if I keep trying it's going to break something. I've removed the rear end and the plate over the wiffle tree, but I can't see anything obvious. The chain is a little saggy and dirty with old grease, but it doesn't appear to be missing or slipping on the sprockets. My next inclination is to take apart the crank assembly and see what's going on, but before I get into that wondered if there's anything else related to the wiffle tree or cables I should look at. Any suggestions on the cause or how to troubleshoot this would be much appreciated! Thanks!