It has been happening to many industries since covid. All it takes is that one O.E.M.supplier to go out of business and that one proprietary part made only by them disrupts the supply chain. Often times you must find a new OEM no matter the cost but in HiFi that's not feasible
Could Krell re- manufacture those parts? Probably, but why? There's no money to be made ....will cost them more than they recoup
I install and repair medical equipment and this is happening often. I just received a part I ordered in Sept of last year. Some parts I'll never see and that instrument, somewhere between $8k and $20k average will get replaced.