The Lionel 6-11333 ATSF 4-8-4 Northern #3759 is repaired (Temporarily). The factory Double-T Universal linkage is too short to set in the too deep cups that hold it. The universal joint arm pins are just coming out of their cup holders, and over time rounding the pins/arms and spinning in the cups.
The engine Universal Linkage Shaft is just long enough to work, but soon fail as the T-pins round and wear. It is just enough to work when first out of the orange box. Failure is soon to follow. It is like the too short screws in the SD45 and many other issues the Chinese factory has created for Lionel Service.
I removed the three screws holding the body and carefully set it forward on a towel. Two electrical plugs fell out of their sockets and were replaced later.
The gear box is only accessible from the top. It was firmly screwed in place. When I opened it, the Double-T Universal Shaft came out of position. There was nothing wrong with the grease or gear box.
The Double-T Universal Linkage showed signs of the T-arms wearing and rounding. When put back in place, the arms were able to come out of place because: 1. the Universal shaft is too short, or 2. the receiving cups are too deep, allowing the Double-T to sink deep in one end and come out of the opposite end. This was the clicking sound I heard when I tried to get the engine to move forward.
I HOPE DAVE OLSEN LENGTHENS THE UNIVERSAL SHAFT ON THE NEW ATSF NORTHERNS.
There are two pictures of the wear on the Double-T Universal Shaft. I twisted and stuffed greased paper into the bottom of the receiving cups to center the Double-T Universal Shaft. Since the greased paper spins with the cup with the Universal Arm, I am hoping the repair lasts for a while.
There is a picture of centered Universal Shaft in the receiving cups and a short video of the repaired engine.
Thank you to everyone for the advice given that helped me repair this engine.
Sincerely, John Rowlen