I've had the above amp for some time. Whenever it is used, there seems to be some kind of cut-out which switches the amp off and on, making use not practical. The amp is never turned up above 25%, regardless of input source. I've opened it up, looked at the fuse by the transformer - it seems to be ok. Is this fault repairable, or should I just binthe amp and replace it? I've managed to break off one of the fuse holders as well..