Replacing Troy Bilt transmission belt

The transmission belt for my Troy Bilt Super Bronco Model 13AT609G766 has slipped. I cannot figure out how to access it to put it back on the smaller of the two pulleys. Any advice?

Viewing an exploded parts diagram online, it’s hard to determine what you can and can’t get to when it’s all together. I’m guessing you don’t have a service manual. You could either order one online, or check with a local Troy Bilt dealer to see if they’ll copy “belt replacement” instructions. Good luck.