This is the weirdest thing I've ever done. I got my very old jigsaw out of the shed and wanted to cut out a speaker hole in an old cabinet to replace an old tweeter.
At first, my saw would not run at all, so I turned the switch on and bumped it on the ground. It turned over about 3 times and quit.
I got the idea to use some DeoxIT® D5, and sprayed some in the jigsaw through the air vents around the armature. Since it's flammable when just applied, I decided it wouldn't be a good idea to hold the saw while turning it on.
I turned it on and then plugged it in, and nothing happened, so I gently banged the unit on the floor, while holding the cord, and IT STARTED RUNNING AS GOOD AS NEW!
I was seriously amazed and plan on sharing this information. Thank you for one of the best products I've ever found.