Thanks for your interest!
I didn't see any, but cleaned it out anyway. Then we put oil on the screw threads, and it still acted the same. The funny part is that although the screw didn't turn real easy the first time I put the plate in (when I had the bobbin assembly finger positioned wrong), it did turn and go all the way in. The problem developed after removing the screw from that operation. The fact that every screw that I try now goes in the same distance indicates to me that something in the threads of the hole is hanging them up.
Is there something I can use that would be most effective in clearing out the threads?
Thanks!
Dayle