wright velke belt smoking??

[D2hornets58]

I have a 2008 36 inch wright velke walkbehind mower and i use a sulky with it. It is the gear driven one with the 5 speed transmission. At the begining of this season i replaced all of the belts. But for some reason the right wheel always goes slower then the left one. so the mower tracks to the right. I have tried adjusting everything and cant figure out why. So to go straight i just have to pull the left brake slightly. The only problem is going up hills so i uasually end up just walking behind it(instead of standing on the sulky)when i go up hills. So today i was mowing a lawn that was pretty long. There was a pretty small hill in the back yard but nothing to big. I was going up the hill very slow because the grass was so long. i would hit the brakes then go forward a little bit then stop again. One time when i let go of the brakes something on the left side started to smoke near the left belt and the mower stopped moving. I couldnt tell what it was so i put the mower in nuetral and turned it around. I drove it around on flat ground and it seemed fine so i went for it again. same thing happened but i couldnt tell where the smoke was coming from. i ended up finishing with another mower but whenever i drive it now there is no smoke and it seems fine. Any ideas???
Thanks

 

[chance123]

look for build up on the pulleys or tires

 

[D2hornets58]

look for build up on the pulleys or tires

Ok thanks for the reply. I am going to be using it tomorow so I will check it out before.

 

[D2hornets58]

I checked today and didnt see any buildup of anything but i used it for a couple of lawns and it seemed to work fine.