From what you are describing, it sounds a lot more like your gearbox is the problem. Especially if replacing the motor didn't get you back up and working properly. I will say that is a little odd that the manual cranking works without issue, but I am still going to steer you towards a new gearbox. If it was something internal in the actual leg, you would hear the noise and have issues regardless of how you lift or retract.
So with all that being said, the gearbox I suggest is the Stromberg... view full answer...