Cub Cadet SLTX Drive System

I have a SLTX 1054 purchased in 2010. It recently developed a rattle (similar to an out of balance washing machine) in the drive system area. Inspection of the area didn't reveal anything apparent, but I have not pulled off the mowing deck for a close look. The noise frequency reduces when the throttle is reduced and stops when the brake is engaged. It definitely sounds like something is loose and banging but so far I have not determined what it is and I definitely don't plan to stick my hand under it when the belt is running. My next step is to drop the deck and lift the front of the mower up for a closer inspection but was hoping someone might have an idea or seen a similar case.

Thanks

Cub Cadet SLTX Drive System