Found this site which seems to have many bits for Durst enlargers, but don't know if they have what you want since all the bits seem to have strange names!
Try having a chat with Stewart Band at Nova. He seems to be only working 1 day a week there last time I spoke to him but he is/was their expert on secondhand bits. I got another red filter attachment for my Durst M605.
Secondhand Darkroom supplies in Witney in Oxfordshire seem to stock bits as well.
In either case I got straight talking without a sales pitch to sell me something I didn't want.
"Names" are only strange to foreigners. Negative insersts are listed at 75 EURO. Consider whether you want H or V. Just last week there were two sets on that site. So put up a "Wanted" item in that auction site
Thanks for the help everyone - Pentaxuser, I think I have met Stewart Band - very helpful. I will try and get there today as Nova is only 20 mins from my office.
(havenly got around to buying the ilforchrome processing chemicals kit yet - but keep eyeing it up. It is only a matter of time!)