Hi Edi,
Thank you very much for your efforts. The company seems to have gone out of business. The email address provided is no longer valid. At least, various forums have independently confirmed that they were also unsuccessful.
For anyone who’s interested, I’ve found the following link:
http://www.troeszter.net/BronicaHome/ServicePage.htm – though it refers to the UK.
I’ll make the lever myself. It only affects the mirror pre-release, which I’m sure I’ll rarely use. Thanks again. Now I’m looking forward to seeing the first result ;-)
Best wishes, Tino