What's the temperature of the empeg like when it shuts down?

It sounds to me as if the amp, or some other peripheral such as an automatic aerial, is pulling too much current from the empeg. Look at the current coming out of the remote enable wire being drawn by the amp or aerial.

If the amp is getting hot, then it is either being used a lot or there is a genuine problem. You could have current runing to earth (DC ground) or it is drawing a lot of current from the empeg. Either situation will not be healthy.

Don't jack up the fuse rating unless it is an absolutely do-or-die, get-you home situation, this is seriously dangerous practice. You need to get this investigated immediately, or disconnect the whole setup until you can if that's not possible. Play safe with your life (and your empeg...)