Thanx for the reply. (I see you are in Missouri. I am in Wichita, KS) Yeah, I even took the gearboxes apart and back together. They are fine. (At least they used to be. The failure happens every 3 minutes even when the controller is unplugged from the motors. It can't be binding. Also it resets with a quick off then back on and works for another 3 minutes, almost like a watch whether or not the box is driving none, one, or two motors. I used this for autoguiding quite a bit 15 years ago after doing the ST4 mod for the Shoestring GPUSB. I kind of got away from astronomy and everything has been in storage until last Spring and I started using it again. It was fine and I used it in both axis for several hours over several weeks until it just failed a couple weeks ago. I removed the wiring from the ST-4 mod and put it back together and NO Change. Works good with or without motor connected for 3 minutes then stops with the yellow light. Before it stops the light is green unless a slew button it held during which time the light is red. The motors speed up and all is well until the sudden stop. (It's not the fall kills you, it's the stop ) Very perplexing.
Thanx for responding.
Headwind H