This is a great machine, and a real sleeper.
Was available in the US through the Military PX system, but not through traditional hifi outlets.
One thing you'll notice right away is that it isn't built as well as many of the old units...lots of jumpers on the PC boards, and the aluminum faceplate is epoxied to the plastic guides that house the square front panel buttons and the headphone jack
There are a couple of trouble spots in this amplifier
1. the Speaker relay in the back of the amplifier (near the speaker outputs...go figure) can oxidize and cause intermittent operation
2. the front panel buttons and switches aren't sealed, and are a natural for oxidation
to get at the front panel controls you'll need to turn the amplifier off and unplug it from the wall. Then
1. remove the screws securing the front panel from the top and bottom of the faceplate (either 5 or 6 all together). Set these aside, as they're all beveled, and the screws that secure the cover aren't so you don't want to mix them up.
2.remove all the round knobs, and unscrew the large nuts securing the volume, Source and REC Out posts to the chassis (and any other nuts I may have neglected to mention
3. The front panel is now free and you'll have good access to the controls. Work deoxit into the volume, balance, Source Direct, Muting, and Bass Intensifier switches especially. I'd also give the bass and treble pots a good cleaning while you're in there
This was all it took to get two good strong channels going for me...if you continue to have issues, look at replacing the speaker relay
good luck and enjoy!