Ferris fast vac belt coming off

[Tklpope]

So I bought a new belt and installed it and it keeps falling off. Seems tight enough. Does anybody have experience with these fast vac blowers? Any adjustment suggestions. It's a ferris is500 with the fast vac collection system on it. Thanks

 

[mechanic mark]

Did you purchase new oem Ferris belt or alternate? If you installed Ferris belt you need to check all pulleys, especially idlers for wear, bearings on idlers do wear out. Also check all hardware for being tight & secure top of deck.