Well, you mentioned that it was working fine before it was painted so there's no reason to think that you have an equipment failure. There's something that either didn't get put back right after paint, or like DaveS mentioned they could have painted a surface where it previously got a good ground and doesn't now. VA doesn't use vacuum dampers, to my knowledge. They use electric.

First thing I'd do is go back to he painter and find out just exactly what he took apart to do his painting, and see if he has any ideas what might be causing the problem. If that doesn't pan out I'd figure out exactly which VA unit you have, and download their detailed instructions for installing the unit. VA has great instructions, and if you track through all of the steps, including verifying all of your ducting and wiring, I bet you find your problem. If not, VA also does a great job with tech support via the phone. Call them up, but not before going through and doing a thorough check of your system.