So yeah, apparently when you put it together, you're supposed to line this tiny groove on the bottom of the grinder plate with a tiny bump on the bottom of the grinder...shaft...thing. the plate FITS JUST FINE if you don't! However, it apparently will slowly rotate with the motion of the main grinder arm, nearly-imperceptibly slowly unscrewing the holding bolt from the front, until it vibrates far enough forward that the little star-shaped blade bit behind it half-falls off its square-shaped portion of the main grinder arm, and proceeds to rattle around and strip the corners off the square-shaped bit.
Cue me cursing, stage 1. Cats look at me askance, James asks if he can help.
I take the grinder apart, fish out the half-mangled raw chicken bones, and carry the pieces over to the sink and rinse them off. I figure out what went wrong, and attempt to put the grinder back together. This is when I discover that A. the blade is made of much firmer metal than the shaft, and B. due to this, when it stripped the corners it neatly folded them back down the square portion of the shaft, forming ridges, which were too wide for the blade to fit over now.
Cue me cursing, stage 2. Cats hide under the sofa, James ducks into the office.
I stomp into the garage, grab my metal file, and try to sand the fuckers off. Then I find that while the metal of the shaft is significantly weaker than that of the blade, it's stronger than that of the file, somehow.
Cue me cursing, stage 3. James hides under the sofa. The cats hide under James.
I finally figured out that if I used my kitchen shears to pry up the edges of the ridges, I could then file them down bit-by-bit. Approximately half an hour later, I got the blade back onto the grinder arm and continued making fuds. I was in a much more zealous bone-grinding mood after that. I may have shouted "choke on it, you bastard" once or twice.
More in a bit, after I have a drink.