UPDATE: POSSIBLY BAD IDEA. READ THREAD.
I have noticed a few people say that the post to the right of the trunk breaks often due to a ball getting wedged between the post and the trunk as it is rotating. Certainly, my machine exhibited that problem: the post was pushed out, stripping the playfield threads in the process.
This modification adds an extra post to help prevent a ball from lodging between the trunk and the existing post. This mod is reversible.
First: fix the post. This post ( http://www.pinballlife.com/index.php?p=product&id=1435 ) is a bolted version to replace the wood screw version that originally came with the machine. Drill through the playfield and bolt this on:
Second: add another post. Take out this bolt, which screws into a tee nut on the playfield:
Replace the bolt with an 8-32 1.5" bolt and screw it through the tee nut all the way through the top of the playfield, creating an extra playfield post: