Does this tool exist??? (for potentiometer nut)

[partsguy]

I am looking to find a tool (if one exists) to remove the fastener pictured in the photo below. I believe these are used on some headphone jacks as well as potentiomenters. (The control pictured below is the scope brightness control on the rear panel of a Marantz 2130 tuner.) As you can see (perhaps barely) it is one of those "nuts" that has a knurled edge and two tiny cut-outs. I am assuming that the cut-outs are where a tool of some sort can be inserted. It measures approx. 1/2" in diameter.

I am also assuming that Marantz must have had a driver to tighten down such a nut. I can't believe that they used my method: inserting a jeweler's screwdriver in one of the little cut-outs and then pounding on it with any handy blunt object!

I did manage to get the control in the photo loose using this technique but I would appreciate any info on whether such a tool exists. Thanks in advance!

[vtech]

Do remember that Techni-tool & GC electronics used to have a couple of wrenches specifically designed for knurl-nuts--not sure if still avail?

Don't have to have a wrench ---there are various ways, A household plier along with a piece of shammy cloth can do wonders... or you can utilize the jaws of a suitable needle nose pliers to land-in the slots & turn the nut. Over the years I've used these methods w/out any problem---only must be careful not to slip & scratch the panel. A little practice goes a long way