After reading the posts on this topic it's left me feeling like a complete idiot and technical incompetent (and I hope this is the correct forum), with a very basic query, but here goes.
Foolishly left my DT50 on standby without realising it. Came back a considerable time later, and found the fuse had blown. From everything I've seen, I'm guessing that there are probably other problems further down the line (valves? transformer?) which were caused by leaving it on. Unlike Bimmermanshane, I will be taking it to a service centre (if I can find one) as I'm definitely not competent to mess around with anything, but I do feel as though I ought to be able to change a fuse, just to see if that's the extent of it.
The orginal fuse seems to have been 2.5A. The fuse cover shows 10A, and the post above suggests it's 1.6A (it's the fuse directly below the power lead socket that's clearly blown). Tried another 2.5A and it blew immediately.
My quesiton is simply what fuse I should be using.
Sorry to trouble you with such a basic question, but grateful for any help.