After finding out that this vacuum is no longer available and there are no replacement parts either, I decided to see if there was a simpler solution to the issue of not stopping or not running. The motor appears to be pretty stout but it does produce a far amount of heat. The triggering relay for starting and stopping the vacuum is on a low voltage circuit board inside the exhaust side of the vacuum canister. It appears to malfunction after a number of years exposed to that heat. To change the $10 relay is just putting off another eventual failure again.
In the photos below you will see the circuit board with the blue relay. I eliminated the circuit board and direct wired the vacuum motor with the double spade connections. I taped the connections for additional insulation. I then reassembled the vacuum and tested it. Works great!
Next I ordered the 15 amp wireless switch and relay from Amazon. I reinstalled the vacuum and plugged the relay between the vacuum and the receptacle. I put the switch in the closet where the wife stores the vacuum hose and utensils.
The vacuum now works like a charm. Turns on and off every time.