More info from Jeff, after receiving my pics. He wanted pics to verify (Registration) this machine. He replied,

" ref: S/N 74498-B

It is definitely a patternmakers jointer, and it even has a spring joint attachment."

(Arms tossed in air) I don't know what the spring joint attachment is, but I got it. LOL.

A: 12-111 table Lock Knob DK -6 $12.00
B: Unable to identify Knob with broken casting.
*this (above) piece/part is probably for some other non-Northfield machine at the auction.
C: Replace the JA-28 fork casting $116.00
D: Try welding the aluminum shield (cutter head guard).

Sonny