81 XJ550 Seca Starter Motor

Hi,
my 81 seca 550 stopped starting. About 3 years ago I rebuilt the starter and it's been great til last weekend. I sprung it open to see if the brushes were worn and in fact they were so worn that the armitures had ground down into the copper contacts on the internal coil. Basically it's FUBAR.
I'm trying to find a replacement
Ideally I'd like to buy a working one and do so for less than a factory rebuilt.
I'm also looking for info though, I can't find the part number for the whole unit to cross reference it, so if you could share that it'd be a big help.
If not a part number maybe someone could confirm cross compatibility with the Maxim version. it looks identical, but once I tried to mix and match a maxim and seca front brake caliper and it turns out they're exact MIRROR IMAGE and not compatible... oops

So I don't know why it'd be the cas but want to verify it's not revers turning or something silly. Maxim ones seem to come up more often.

I also found a mitsuba starter that looks right from a Radian (YX600?) which as far as I can tell is the descendant of the XJ550 and could reasonably be correct?

Open to suggestions, inputs, or starters for sale!

 

Well! I found the whole assembly part number shortly after posting this;
4G0-81800-60-00
Looks like it fits' all of the 550s and ONLY the other 550s.
But some more digging shows it's the Mitsuba YS-12 which is a 12 Volt, CW Rotation, 31 tooth w/ 13.3mm Gear
and is also cross listed as 3KM-81800-00-00 which was used in the FZ 600 FJ/YZ
Soooo.....
that helps me. Still looking though - if anyone's got any XJ550 starters or FZ600 of Mitsuba YS-12s hah!

 

I might have one off a 82 550 so I'll check it and send you pictures today.