Thanks for the MIR information. I find them interesting but don't know much about them. I saw three weeks ago a MIR machine with "warm magnet" was not selling on ebay about three weeks ago. It was pick up only and the seller didn't have any bids at $1000.
"Warm magnet" is probably a synonym for "we f**ed up and someone activated the emergency quench". No wonder that this didn't sell as the emergency quench just opens a valve connecting the liquid helium tank to the outside-> pressurized helium gets released->temperature rises as helium level drops->the current (>10A) still circling inside the magnetic ring suddenly encounters conductors with a finite resistance-> Ohms law kicks in->conductor gets hot->helium and nitrogen boil off explosively->fun times.
Chances are that you have to get new magnets as they probably got damaged whenever you punched that emergency quench button (remember: the conductors do not have an electrical resistance so the diameter of said conductor can be rather small as it will never heat up due to the current [except when you quench it]->small conductors do not react well to extreme currents).
Btw, that is the reason why MRIs have two seperate emergency shutdown switches:
One that will just kill the power, but leaves the magnets running->normal safety switch
One that will quench the magnet and therefore make sure that the magnetic field collapses->only for MAJOR fuck-ups as the cleanup is rather costly
Here is a video where they quenched an old MRI magnet:
One a sidenote: MRIs aren't actually the machines with the most powerfull superconducting magnets out there, that honour goes to NMR spectrometers: Those reach up to 24T while MRIs "only" go up to 7T. But that's not really a fair comparison as NMR spectrometers can only fit 5mm wide test tubes while an MRI can fit a person.