One specific direction or any of them? does it happen with the seat empty?
If just one direction, then I would suspect the switch or the motor causing too much draw. If it is any of them, look at the wiring harness, maybe something git pinched or cut or frayed over the years.
I know sometimes on maxing out the up and down travel it puts undue stress on wires and connectors. Gets worse if you have stuff under the seat in the way