Okay, I popped the wheel off and had my wife work the shifter while I observed. There was a little bit of play in the shift linkage, but the shift linkage arm was basically just flopping around. Obviously, those rubber bushings are shot!
I imagine this could this be the cause of the crunchy shifting...
I should probably replace the shift linkage with the above short shifter while I'm in there.
Edit...
Damn! I wish I knew about only944.com before I bought a shift level from Penguin! I think this one is much better:
https://www.only944.com/partscatalog/only/shifter/