It's not the knob that controls the speed or the RJ11 connector. The problem is one of the four little dials that you use to select the locomotive address. They just pop out but it's tough to get all five little prongs lined up when you try to plug it back in. That's how I broke off two of the prongs. And I am not interested in paying Digitrax $25 to plug one back in and being without the throttle for a month. I do have a plan. More later.
Pb
If the shaft is snapped off and the remainder is still inside the knob you may as well send it back to Digitrax. I recall they have a flat fee repair. If you are comfortable with delicate PC board repairs you may want to replace the encoder yourself but you risk damaging other components.
http://www.digitrax.com/support/returns/
I put smaller knobs on all my UT throttles.
As far as the RJ11 connector you can get a telephone crimping tool and repair these yourself. The tool is handy for making up your own Loconet cables, too.
Hope that helps, Ed
Has anyone else knocked one of the little dials off their Digitrax throttle when placing it in the Micro-Mark Universal Cab Holster? Does anyone know how to repair said throttle without sending it back to Digitrax? I already broke off one of the little connectors and would need a new dial.