notsobigjoe, never had a problem with the jacks "locking up". I would need more info to help identify the issue.
I did have a problem once with the single motor really straining to lift its side of the TC. I switched it with a motor from the opposite side and had no improvement. I then checked my Trimetric and my battery was fully charged. I checked all connections, found no problems but the lift worked just fine. Point is, had to be a bad connection.
After that experience, I made a set of jumpers that I can use to go directly from any 12v source to any of the three jacks to raise or lower the jack. So far, the jumpers have been a waste of time cause they have not been needed.
Wayne