Hi Neil, Just saw this vid... A couple of weeks ago (memorial day 2024) a happyjac strut failed on me when I was leveling out our truck camper (with chuck and drill). A front one. When I say failed' it just gave way and the whole camper started to tip over but fortunately stopped before going all the way over (on me by the way!) scared the shit out of me. If the jacks had been fully extended, then that camper would definitely have rolled over and dinner would have been on the ceiling. I think your video is exactly what happened. The threads stripped out. Ordered a 4220 Jack and have to go back to Maine to replace it to get it back on the truck.
They have some factory blems for the legs 750 bucks for two brand new ones that 3000 lb legs complete use your motor and gears and I got 4 and the four of the plastic motor base and the top and it worked out great does not kick out the motor controller that you have to unplug and plug back in to reset power. And most of your weight is on your front jacks and the front jacks are bigger than the back. I had 4150 in the rear and 4500 in the front the back ones are like 1500lbs and front ones are like 3000lbs . So good luck hope this helps .
I bought 2 new jacks. I put the new ones on the front, 2 good ones on the rear and have one as a spare. I had to order them and I believe they were around $500 each.