I am actually very bummed that I have not gotten a chance to work on this machine and/or see it in person.

However, here are the pictures posted with the author’s persmission.

It is a 4-push button knitting machine with a screw-on handle and a clip-on vintage row counter.

The buttons are activated using the special ratchet tool.

With the exception of the color ( a distinct swamp-green), this machine looks and will probably act very similar to its other 4-pushbutton sister, Brother Profile 551, which I described in my blog in detail. If you like this type of patterning mechanics but would like versatility, check out the Brother KH800 knitting machine: it has the same ratchet-based needle selection mechanism but it is actually punch-card based (thus, more unique needle combinations with 12-stitch repeat). A bit simpler option is 8-pushbutton knitting machines, like Brother KH585, Brother KH588, Brother KH710, etc.

Because of its similarity with KH551, Brother KH531 might be compatible with the  Brother KR551 ribber.

Another distinct difference is the opening side cover (on both ends) and a metal (not plastic toolbox):

The machine comes with a standard set of tools, including a ratchet tool.

It looks like Brother KH531 was released onto the Japanese and Western markets: the carriage below has Japanese markings on the buttons, while the very first pictures in this blog has words only in English.