My neighbor has a couple 275 amps that are not used, older and need some attention. Definitely out of warranty, and service repair places say mcintosh says best to go to a service center. This was as of two months ago.
Currently don't know what timing is for mac. They don't like to be in the servicing business that's why they have a net work. CJ is a good place to send gear and they don't take that long.