Here is a picture I took of mine during my teardown. There were no problems with the ball getting stuck there.

DSC00954.JPG
DSC00955.JPG

Wait... I just noticed that in my picture, the wire gate is on the opposite way that yours is. See how that hook is on the other side? Our brackets are installed the same though. Maybe try switching the gate around?

I think that's not sitting dirt, that's ground-in filth where the ball traveled. I had to sand a lot of that out.

I found another shot that might be helpful.

DSC00780.JPG

That's a great idea about the topper. I think I'll go look around at Halloween stuff tomorrow... perfect time of the year.

Also I'm reassembling my HH this weekend after a total restore. Did you take a lot of teardown pictures? I'm worried I didn't take enough and it would be awesome if someone else has a set. I put together the upper playfield and I ran into a lot of "what size screw goes here!?".