I dismantled an old Mach III cartridge, and separated the cart. blade assy from the little plastic clip thingy that connects the Mach III cartridge blade to the handle...
There doesn't seem to be any way that I could fathom how the Mach III blade can be attached to either HB blade adaptors.
The "ducktape" idea did give me a giggle though...
So I'd really like to hear from TimmJ EXACTLY how he did what he claims to have done...
All the best!
TG