I can hear the motor running but it won't budge. Goes back to front, back tilts, headrest...but no up/down. Passenger seats works great. Memory functions used to work for #3 only but now that's stopped too....wheel and mirror work 4.0.

 

It could be the drive cable has come out of one end.

I had the same issue, however when i removed the seat to put it back in i found the base had snapped on both sides so had to get it welded first.