What does recall means in this context? De-energizing the superconductor and shipping it back? Seems like a waste and a planning nightmare.
A surprising amount of maintenance can occur while the magnets are cold and energized. My armchair-uniformed-guess is that they can replace the not-always-working relief path without venting.
Remember, cryostats are like Russian dolls suspended on torsion wire. You want the mass of the metal inside to be as low as possible because it forms cold bridges to the outside world and increases the boil-off rate. Quenches should not happen once the magnet leaves the factory, but until that point it's not uncommon for a machine to have several "training" quenches as the (typically NbSn or NbTi) superconducting wire effectively anneals in place. A fixable giant hole in the top (with a graphite, insulating series of bursting discs) is the approach usually taken.
Every MRI machine quenches and vents. The question is what is different, in detail, that heightens the risk with this machine.
your response is like saying "the engine wont work" as a complete explanation for why a type of car has more automotive problems than another. Then, when a mechanic is curious about the nature of the failure, you call them stupid, saying "I already told you, i said it doesnt work!"
I certainly hope you are not in charge of solving problems in any professional capacity.
The design can't safely accommodate the level of energy that ends up in the machine if its clogged.
In the spirit of analogies, it's like asking why a 10 oz glass overflows with 200 degree water and a 10 oz glass doesn't overflow with 100 degree water. It exceeded it's capacity.
There's nothing more complicated to it, you could call in an MRI technician, get the PDF manual, talk to several doctors, disassemble it and put it back together, and learn no more than that.
You got extraordinarily rude and personal, I hope you don't do that often on HN, that was an outlier in my 13 years here. I hope all is well and it's an exception.