Like, not just jammed, the mechanism no longer functions.
Oops.
This "free" project is no longer so free!
(I'm covering some 1/2" plywood in 2 layers of cotton batting, and then stapling part of an old cotton sheet over it. It will give a nice firm surface for pressing, which I find I like even in garment sewing, not just quilt block construction. The staple gun quit on batting layer #2.)