YEAH, the RT-909 pinch rollers really do turn to GOO.... especially with sunlight or repeated alcohol exposure or cleaning. Almost unavailable these days... once the pinch rollers go "out-of-round" the tape will wander all over the place. Check that the twin capstans are totally clean of debris!Actually its very, very easy to make the RT-909 FUBAR!!! Not even mentioning the many "failure modes" that can also mess you up - like really worn heads; someone tweaking the half a dozen internal controls for torque and tension; the main flywheel belt being stretched and basically non-elastic; and wandering, or disassembly where someone lost those little nylon "balls" that the flywheels balance on; gee I could go on and on, but you get the idea...
-Steven L. Bender, Designer of Vintage Audio Equipment