When our TV lift stopped working in the down position, it was because that momentary switch went bad. I pulled the switch out and removed the two wires from the switch. When I touched and held the two bare wire ends together (simulating pushing the toggle switch), the TV went up. When I touched and held the two bare wire ends together again, the TV went down. After a few repeat tests, it was obvious the switch was the problem. I replaced the switch.
Since the TV had been stuck in the down position, I thought I was going to have to drive it home in the down position, Interestingly, when the switch began to fail, it never stuck in the up position. It always stuck in the down position.