The Arrow Antenna for satellites has an optional diplexer that allows easy operation of 2m and 70cm from a single feedline. I've used this configuration for over ten years with no problems. I'm not sure, exactly, what happened but the diplexer failed. After ordering a new one I started digging into the hardware to see if I could see anything that was the matter.
Looks like one of the surface mount parts got a little warm. The picture does not show the hole that had melted through the shrink wrap but the bottom right component definitely got too hot. The solder is completely gone from one side which was definitely affecting the circuit. I'll likely try to repair this even though I have a new one in service right now.