hifi engine

Audiolabs 8000A stopped working

My 8000A stopped working, this has happened before and I replaced the fuse at the back near the AC power cable but this time replacing the fuse is not helping, the light goes on but no sound is coming out of the speakers. My teenagers used it last and said it stopped working but prior to that it was cutting out and of course they did turn it down or off. Anyone know likely issues and if it's repairable. I bought the amp in the early 1990s, it's a 120VAC unit and the thing was fantastic. I would really like to repair it. I live in Ottawa Canada. Any help or advice would be greatly appreciated.