Re: 50 MB in the '80s?
"They didn't damage ALL the drives and disc packs......"
IIRC on set of operators did just that with the System Disk - going along all the 8MB drives - and also ruined the reserve "master" System Disk.
In the Kidsgrove Systems Test commissioning the 8MB exchangeable disk drives were subjected to a thrashing that moved the heads to their extremities at high speed for some time. The unit vibration was definitely severe.
When the first 8MB disk units arrived for the prototype System 4-70 mainframe they had to be commissioned by union approved engineers from the factory. By the time the second prototype arrived the local engineers were allowed to install the disk units.
There then came an day when it was discovered that disks formatted on the second machine wouldn't work on the first one. Much head scratching until someone spotted that the disks on the first machine rotated in the wrong direction. The heads were symmetrical - so they flew ok - and the prototype's disk O/S was initialised from magnetic tapes.
The reason was well known to local engineers. The System Test area had its 3 phase wires wrongly coloured. There had never been a time when there was no equipment installed - to allow the problem to be corrected. The local engineers had to remember the correct wiring. The visiting engineers had come in at a weekend and no one thought to tell them about the discrepancy.
Apparently card punch mechanisms did not take kindly to going in reverse.