I'm an idiot.
I replaced my rear discs and pads, had to bleed the brakes a little, and didn't tighten the rear bleed nipple very well. It vibrated loose and now it's gone... With what do I replace it? Trying to find a parts list or even caliper model numbers is defeating my google-fu.
Can anyone point me in the right direction please?
Update: Found the answer, see third reply (http://www.ducatimonsterforum.org/index.php?topic=66659.msg1230216#msg1230216).
Something in here:
http://www.yoyodyneti.com/Category.aspx?CategoryID=3014 (http://www.yoyodyneti.com/Category.aspx?CategoryID=3014)
Call Fred and ask....
Sounds like a job for SpeedBleeders!
Thanks for the help, Speeddog, unfortunately I wasn't able to make that page load from Australia (though it's working today, strangely). But in the meantime I made some progress.
According to this page (http://www.thisoldtractor.com/gtbender/brembo.htm), the brembo rear caliper on the 1993 M900 is PartNo: 20.5161.42
Which led me to this PDF (http://www.totimport.com/downloads/brembo_oem/20516142.pdf%C3%A2%E2%82%AC%C5%BD) which has the breakdown for the caliper itself, including dimensions, and most importantly, the 'available spare parts'.
The bleeder screw is PartNo: 105.3246.11
(the dust cover is PartNo: 205.1502.10)
The bleeder screw is described as 'F8 Style'.
So now I'm off to find a local source for this part. And then I'm going to screw it in tightly. =/
Not too tight! Aluminum caliper, not very strong bleeder screw. Maybe about 5 Nm. or about as tight as you would make something with a screwdriver.