You didn't say if turning one capstan by hand moves the other in the same direction... Anyway its probably not the belt if there is a burning smell, it could be one of a dozen things, and quite costly to repair. Check and see how the heads are doing, if you can catch your fingernail in the head wear groove, it might be time to consider another buying machine. Of course, trying to find a working RT-909 with low head hours... these days, expect to shell out over $600. or more.

If you have a local Radio/TV Repair place, where the guy is actually more than 20 years older than your RT-909, maybe he can find the fault, but he may not actually have the RT-909 Service Manual, which can be bought from me, or from several other sources.

I'd never tell or suggest someone ship that set across the country, shipping damage is too likely, on top of whatever fault it has now, and I hate to work on sets that are that heavy anyway.

Good luck,

-SB.