Sorry to hear that Charles - don't think we can suggest anything else at this point. This is one of the reasons I avoid Velodyne products, they just aren't easy to repair as they age, while an old SVS, Seaton or PowerSound sub will always be repairable.
The only suggestion I can offer in that case is to pull out the accelerometer and try to see who the OEM is. They might be able to get a similar device for you. Beyond that, you might be stuck.
A fluttering sound likely means the driver is blown. You will need to contact Velodyne to see if they will sell you a new driver assembly. It should be fairly easy to replace, you just remove screws to pull out the old one.