Well, I got a Singer Monogrammer for slant needle machines on ebay for a few bucks, and it just arrived.
The good news: it's in excellent condition.
The bad news: No way in heck will it attach to a vertical needle sewing machine, such as mine. The mounting point is angled for a slant needle machine, and if you try to angle the device to make it fit on the shank of a vertical needle machine, you can't lower it enough for the holes for the mounting screw to align. I had wondered if the mounting point was on a replacable part, so I could perhaps scavenge the relevant part from a common, inexpensive buttonholer to make a FrankenMonogrammer, but it turns out to be molded onto the metal casing of the device.
Conclusion: Don't buy a Singer Monogrammer for slant needle machines unless you in fact *have* a slant needle machine.
The device itself seems nice enough, I think if it fit my machine, I might be very happy with it. It makes small elegant shaped letters. The included template is used to position the letters and mark the fabric to determine when they're done. (When the letter is completed, it just keeps sewing unless you stop: it has to return to the starting point, which would mess up some letters if you don't stop at the appropriate stopping point.)
The device drags the fabric around in the shape of the letter, but unlike the Singer Buttonholer, it does not jerk the fabric back and forth in zigzags, assuming that the machine is a straight needle machine. The Singer Buttonholer for slant needle machines assumes that the machine is a zigzag machine, and the width you select for the zigzag on your machine will determine the thickness of the lines of the letter. Remembering that this means that the width of the line of the letter will "flatten" on horizontal lines and "fatten" on vertical lines, this implies that the letters will give the impression of looking like calligraphy. If you set the machine for straight stitch, you'll get a letter in a fine line instead of a calligraphic letter.
Also unlike the Singer Buttonholer, you can replace the cam for the letter without removing the device from the sewing machine, because the door to access the cam is on top of the device instead of on the bottom. I found the cam rather difficult to remove from the device though. It's not easy to grip, and there's no real space under it to allow you to get your fingers underneath to pry it up.
In general it seems like a nice tool and I wish they still made it, with mounting points suitable for current model machines. I intend to photograph mine for a descriptive web page about this category of equipment and for my book, and then put it back on ebay.
Tom Farrell