[Ron Ramirez]

Actually, the hex holes in the slugs are the same size. The proper tool is narrow under the adjustment head to allow the lower core to be adjusted while not affecting the upper core's adjustment since the "neck" of the proper tool is smaller than the adjustment hole.

If I can find a picture of one later on, I'll post it...

Yup, consarn these doggone newfangled contraptions anyhoo...