My Crate BT350 just suddenly stopped working....no smell, nothing visibly burned or seemingly overheated. The ohms dropped slightly below 4 and it started to distort...blanked out, came back on and the sound gradually diminished to nothing at all! The unit comes on when it is turned on...but has absolutely no sound except for a very light unit sound when energised...no sound signal though. Any idea what has happened ? and is it fixable? Where can I get the schematic for this unit?