I have ruled out the switch by swapping switches and there was no difference. I have reseated the fuse and the right rear always works when the left front fails so I think this rules out the fuse. The motor replaced 3 - 4 years ago was OEM. I hate to replace the motor just to see if it solves the problem...when it works, it works very normal. I suppose the thing to do is pull the door panel when it is failing and see if there is electricity to the motor. I have had the door panel off many times and see no moisture anywhere. It has me stumped.