Mk V combo died while not in use.

I'm going to start looking for small green men with tools in their hands to catch them while they sabotage my gear.

Combo stood still for 2 days and when i got back to it, switching power on blew the fuse. Repeated that with fuse i nicked from my V head. Since i ran out of fuses (since my marriage i have experienced series of abduction-cases where tools, spare parts and small case of glass fuses mystically disappear), i have time for writing.

This - as i know -can't effect to this but just in case... I had combo speaker and Three Quarter cabinet in use. To test drive V head i removed 3/4. Speaker cable was left to 4 ohm jack. But. Mismatch is not that bad. There was just power switch used. No signal whatsoever.

Only thing that could have effected to this is the cabinet under the combo. Since i tested my overhauled V head, i used some serious volumes shooting to that. But seriously. Are these things so fragile that when tubes cold they can't stand even this amount of resonating?

Going to do the routine with power amp- and rectifier tubes as soon as there is some fuses to melt again. However this is getting in to my nerves. If this is the normality with older Mk V's, i may start a career as a fisherman. With weights in my fishing net from a bit expensive side :/

Got some fuses so i could start my testing. Now this seems like rectifier tube failure. Not sure thou. Kinda odd behaviour.

Power on with all tubes attached--> fuse blown. No sparks anywhere. Double checked like this. Nothing but blown fuse.

So it seemed like something more expensive than tubes is wrong. At this point i have to confess i contacted to several ancients using loud voice and if i don't remember it all wrong, i also kept a complete lecture about organs a mammal needs in reproduction process.

All tubes off and power on---> Fuse intact (hint of hope started to sneak in)
Rectifier tube in---> All ok
Then i put tubes in using order 1,4,2,3. When i put the last one in, huge flash in rectifier tube but fuse ok.
Changed retifier tube to old one used in V head--> No flashes. Double and triple checks.
Changed fuse to new one just in case, because of the flash seen earlier.

Sound tested for about one hour. Didn't explode in fire and smoke. Guess it is ok again.

But this makes me question, why the flash happened only when all tubes were in? Is there something i'm missing in here?