Hi, I have a problem with myJVM1C combo. The clean channel has a substantial drop in volume when I use the footswitch.

However I suspect the footswitch may be the wrong switch: I don't see a code on it to identify the model, but it has an LED. (Metal chassis, single button, simply branded 'Marshall' and not marked 'channel', if that helps identify it.) The LED lights up on the clean channel, rather than on distortion. 

Are you abIe to say if this issue of the volume dropping is likely to be a result of the footswitch - or indicative of a problem with the amp itself?

Many thanks