Stannah 229?

The chair when plugged in and key turned to on will go up and down automatically continuously with no one siting in the chair.

If you hop on to the chair as it's going down when it reaches the bottom the chair will stop and the motor will make a small straining sound and not move, hop off the chair and it will start to move.

Chair came with the house it was a foreclosure sale so no info on site.

Might it be an easy fix, or just call a service tech?