Update:
So I threw the kydex insert from my short Combat Master in my toaster oven and totally nuked it! I think I may have left it in there too long--2 minutes at 300 degrees.
I tried again on my long Spec Ops to fit my Ratweiler and that went much smoother. This time I left in for 30-45 seconds then tried to insert knife, repeat as necessary.
It's not a difficult process if you're not a goofball like me.
I sent an email to Spec Ops to see if they can sell me another kydex insert--I may be SOL.
