BUT!, I've just switched off the scope and tried to switch it back on and it's not working.
Oh gawd!, here we go again. I've checked the voltage from the plug and it seems ok, checked the connection to the scope and that seems OK as well. Sometimes the centre pin can cause a problem and needs expanding with a small scew driver to fix it. But I had that problem the other month and I fixed it then.
Looks like the on/off switch is bust, I'll have to take it apart tomorrow and do some more testing.
Shame actually, it's gonna be really clear tonight, first time for ages.
I'll keep you posted (hope it doesn't have to go back to be fixed) .