Haha - the internet is amazing!
I am having the same exact problem.
The buzzing just started yesterday.
Prior to yesterday, the motor (I assume) has gotten weak and sometimes the shade will not go down at all.
I was going to try and disconnect the motor as well, but thanks for the tip on just pulling the fuse. I am headed outside right now to pull it.
After that I will begin searching for anyone experiencing another problem, when changing the position on the driver seat (pre-programmed) between setting 1 and setting 2, it makes a loud noise, like something needs to be greased.