I have a Troy-Bilt 13AN77TG766 lawn mower. It won't go into forward or reverse. When I look underneath while the engine is running, from the motor pulley to the transmission pulley, the belt is not turning. It looks like there is no tension and the belt is too loose. So, I replaced the belt thinking it had stretched out, but the replacement does the same thing. When I look at the diagram, I can't see a tensioner of any kind, so it looks like it is all based on how tight the belt is on the pulleys. I think I'm missing something obvious. I don't think the belt can be routed any other way.

If anyone can offer any suggestions, I'd appreciate it. The only lead I am working is that the replacement belt said it was 69", and the original MTD belt had a spec of 68.9. So maybe it's that 1/4", but the old belt has that slack and more and reacts the same way. ??

There's an adjustment somewhere...

Regards,
leaning

 

If you replaced it with a generic 69" belt, it will never work right. There should be a spring connected to the arm with the small pulley on the upper belt that goes from the variator to the transmission pulley. This is what keeps things tight. Put your speed lever in the fastest setting and see if it goes. If not, check to see if that spring is there.