So I got news from the company who specialises in hard drives recovery/repairs and the MMI's completely dead. They said they could retrieve the data on the platters for about $800 though. I'm not kidding. That's how much those guys charge for a HD recovery. That's a LOT of dough.
Thankfully I didn't have to pay anything.
I'm still looking for a replacement drive... Contacted a guy about a month ago, he said that he might get some NOS MFM drives soon.
I wonder if I can just stuff a 20mb drive in there... How does the Hyperdrive manages the C/H/S data of the drive? Dunno.
Nah I'm better off waiting for an exact replacement. At least in the meantime I can just use it as a "normal" 512k as everything else on it works! Time to play Dark Castle! Yay!
If you guys know a place here I could get a working MFM drive (that is: tested, a lot of those are untested aka dead), I'd love to hear about it! I should check vintage PC hardware stores... But I don't know any good ones. I'm not a PC kinda guy.