2010 Shuttle 6 Rattle Sound in Slow Speed

[jabber101]

Hello,

I recently purchased a used shuttle 6 from dealer in FL who got it out of a lease. Off the bat noticed a rattle sound from the drive shaft, they swapped the input shaft from another cart thinking that was the problem. The sounds did quiet down some but you can still hear it when you slow down or just start to go. I had another dealer in my new location look at and they informed me the cart was leased to a Marriott property and the controller has custom programing to where the regen braking is set real high and they think this is what is causing the sound. He explained to me like the regen was kicking on while driving. They said they could not program anything other them the speed because it was a custom flash from the factory. So where do I go from here? Any suggestions?