Power windows

Driver's side windows intermittently not working. Took panel off and hit motor/regulator and it works. It's like a dead spot on a brush. There is a set screw on the end of the regulator. Is this an adjustment? Anybody have any specs on this.

More than likely a bad/corroded connection
I use to have an old cutlass i use to drive around with a rubber mallet just to get the windows up and down,haha car was a pos so i never did fix it....