Hey guys!
I have that same model in equal condition! I learned from RJ Vanik in the vac club that you can shroud the motor with a white cotton terry cloth bonnet with elastic border (the kind that I think is supposed to fit around those electric car polishing buffers) in other words, the type that is used to wax your cars. Generally, they are really cheezy these days so the poorer the quality the better! Why? because the thinner they are the more air they will allow to pass through to the motor. I have asked RJ if there is any possibility that it could harm the motor, causing it to over heat and he said no and has tested this technique to some degree. When the bonnet gets dirty, simply pull it off and toss into the washer! You will notice how quickly it turns grey/brown! Give it a try and let me know what you guys think!
Louis