Take the passenger switch out, pop open the 4 small tabs. Inside you will find 4 contacts and 2 w shape metal tabs. Most likely one of the the contacts has a carbon buildup. Use sand paper and electrical contact spray to clean. A blob od dielectric grease will help keep the carbon at bay for a while. You can get the contact spray and grease at most auto stores. Failing that try somewhere like radio shack or digikey.
Figured it out. I don't think that it's the motor. The window is scraping against something inside the door. Rolled up my window one day and found a nasty gash in the tint on the inside of the car that wasn't there before. Don't have a solution yet.