Until I can find the part, in the meantime I’ve taped it into the ON position and I just disconnect/reconnect AC plug to power cycle. Not elegant but it works so far.
I have a new HX and didn't realize the Mission pedal I already had wouldn't work on Line 6, so I modded my old Crybaby this way. Then I was pondering how to spring load and I had a lightbulb moment, so I made this little vid. Prepare to be amazed!