This machine is a KnitMaster Super-Plus 7500 (203 needles) with a Ribmaster ribber.
It dates to approximately 1957 according to information on the ribber that was found in a Modern Knitting Magazine printed in 1957.
Missing from this machine (if it ever included them, and I wonder if perhaps they were optional) is the plastic ball shaped yarn holder with tension mast that would have sat on the back of the carriage almost like the AM3 Knitting machine as well as the wool inserter which can also be found on the AM3 and would only be used in conjunction with the yarn holder.

This leads me to conclude that these were both optional since they are both missing from this unit. Cast-on and knitting works exactly like the Knitmaster/KnitKing 4500.

This machine includes a Ribmaster ribber which is an Every-Other Needle Ribber.

This machine shows quite a bit of use. Pictures show the machine and ribber apart and being cleaned thoroughly. Quite a bit of impacted fluff was found in the machine and the center half or more of the needle bed shows wear where the needles moved back and forth. Paint is chipped. Wear does not affect performance of any aspects of the machine. All parts are intact and have been cleaned and luricated as necessary. Knobs on the carriages are of a ivory colored hard plastic and show some cracking but not something that affects use either.

Cleaning in Progress:

Main bed:
Some intersting things to note: The needle bed comes apart in sections...reminds me of the current appearance of the bond, and the metal bars that the carriages slide on also hold the needles in place. (Bond use retainers too). Also, underneath the needles on the mainbed just under the front metal bar, is a black thick wool strand covered with a thin plastic cover strip which is a means of keeping the needles in place, much like our current foam bars do on the current machines, and some Bond knitters have used this technique to keep their needles from moving at will too. Works well!