Darn it! I thought that that would get it.
After cleaning under and around my block, it fit in much better - it moves very smoothly, but I wouldn't describe it as loose by any stretch of the imagination. I had to pound the living hell out of lever to get it out, so there was a lot of crap around mine. It is pitted and a bit rusty. If I had to guess, I would say that it's steel, but I'll honestly say that I'm not sure that I could tell the difference.
As far as I know, there's no where to buy parts for these stoves. I'm wondering of your block is original, but the "U" that I (poorly) described is worn off. The "U" on mine is raised, and I would guess that the point of it is to allow the fines to fall underneath it, then sweep them into the fines tray. The bottom, closed part of the "U" goes toward the front, and the legs are on the sides of the block. I wish that I had taken pictures of it. I would pull it apart again to get some, but it's 15* here and going down.
Even if yours is loose and some coal is getting under it, I can't comprehend why it still won't feed something up onto the grate. When the feed motor is running and the block is moving, how far back and forth does the block travel? What's the RPM of the feed motor? When the stove is empty and without a fire, does it appear that there's a smooth, open path for the coal to follow from the push block to the grate? I wonder if the coal is getting underneath the block (or beside it) and jamming it. Is the block loose enough that you could slip a thin sheet of steel underneath or on top of the block to "tighten" it? That's probably not a permanent solution, but might give us an idea of where to go next. After you started the fire and put coal in the hopper, did the block continue to move even as it was making the grinding noises?
I would pull off the hopper, run the feed motor and pour just a bit of coal in at a time to see what happens when it's trying to feed. Don't worry about lighting it, yet, just see what's happening through the stoking process. If the coal is jamming underneath, you could CAREFULLY press down on the top/front of the block to see if that stops the grinding noises.
I was hoping that we'd start talking about timers and T-stats because the stove was running. I wish that I lived closer to you because I would be happy to pay a visit if I did. We'll get this!