I would say it is possibly a fault in the power supply, maybe a rectifier. Unless you have some basic knowledge of electronics, a multimeter for testing, and a soldering iron for replacing components, there is nothing much you can do.
I repair amps and live in Aberdeen, if you live near there contact me.
enqiries@amp-repair.co.uk
Robert Hossack
June 2008
If the fuse blows immediately upon insertion, you most likely have a short somewhere further down the line. It will probably end up being cheaper to replace it rather than repair it.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix guitars.