I've made progress - I got the stuck bolts out, but they were badly stripped in the process. I thought the thread would be damaged too, so ran a chaser through, and that only stripped the tool as well, which was puzzling.
It rurned out the blades themselves were out of alignment and the toughened steel was stripping any bolt put through.
Once I took everything off and cleaned out all the compacted wood, I could get the blades back on properly aligned.
What a monumental PITA.
Lesson learned - release all all blade bolts gradually together, not one at a time.
I had to take the feed roller off to get at everything, and now facing putting it back on. A lot of this would be easier with two people, but I have to do it on my own.
Any tips on how to get that spring compressed and the rods back together without busting another vein?