Are the belts slipping? Coming down requires more tension pulling against the spring. So you need to watch to see if motor is rotating but the pulley slips on the belt. If so, change belts. Go to automotive store or Home depot to get a similarly sized O-ring.
If motor only turns in one direction, PCB can be bad, or a wire is off/open to the PCB. The panto board is $25 or $30. G