I'm a little late to this party, but the nostalgia... The very large MFM and RLL drives .. let's not forget how much fun SASI and SCSI drives were back in the 80s.
I believe MFM is whats used for floppy drives and tape storage, while RLL went on to become the standard encoding.
Also I believe original large format HDDs needed to be right side up, with the head on top of the platter, because the head "floated" over the HDD. I'll have to double check that one.
To the guy who is having a bad drive issue, I highly recommend using a write-blocker (these are sata cables that don't allow anything to be written to the drive at all, and doing a full sector by sector imaging of the full drive, all sectors, and be sure to enable the "continue on read error" option with most disk imaging tools. Clonezilla is a good one that you can make a boot USB. Whatever you use, it's best not to have the backup program try reading the file systems. I dealing 'dd' type of reading and writing is going to be best for a forensic image. The only thing that can recover beyond sector-by-sector is using diagnostic machines. One method used by LEAs is a clean room platter transplant. That's where you open the drive, remove the platter, put the platter in another drive, and pray. You need a sealed clean room and extreme care with the platter. But yah, like everyone else said, early onset drive failure. I'd be curious what the extended SMART test data comes back as. A drive damaged physically, even if not spun up at the time, can end up with a very very slight alignment jitter. Gravity is still gravity, and a drive with even the slightest imbalance will most likely have trouble vertically.