dewalt d500 wet and dry vacuum cleaner?

Not familiar with this as I stopped working on cleaners back in 1993. Fort the record I know only upright cleaners and turbo brush heads had belts no cannister( that's what this type is referred as)have a belt, but don't hold me to that as I said above.
Try:
Remove the hose and place hand over the opening of the vac see if there is suction....No then try cleaning or replacing the filters, if any especially over the motor. If there is suction then the pipe is blocked eas a bamboo can gently down the hose to try moving the blockage, gently stretch the hose when feeding the cane down. check the seal around the casing where it is opened to remove dust/water that it seals properly that's another source of losing suction.

bob
April 2013