replacing my vintage luxman R105/drives 4 Ohm Magnegplanar speakers

Hi there- I have an R 105 that after many years of faithful service, is not sending signal to my 4 ohm Magneplanar speakers. I am hoping it is a fuse. If that is the case where would I get one? The unit turns on, just doesn’t sent the signal. I am a professional cellist and audiophile and have loved the sound of this wonderful receiver.  How rare it is to have a piece of equipment turn on every time you push the button for dozens of years.
If it's not a fuse I need to find an affordable replacement that would safely power my beloved maggies!