My Express recently really hasn't sounded that great and as a result I've always gone to the Marshall. In fact its always been a bit intermittent in the past as to whether it sounds great or not. Well I found out why today! The bright switch was faulty. Don't know what made me think to check it but I measured resistance between the contacts when it was on. It wasn't much resistance but it may have gone down a bit when measured with a meter. Anyway swapped it out and the amazing tone is back!
So there you are. Don't forget the switch
