Fuse blowing randomly

[fossilshark]

Sometimes the fuse blows on startup but i put a new fuse in and then it starts up perfectly, could the filter cap be too big for something to handle the startup current draw? The amp is 50 watts and im running it through a custom 4x12 so i dont have to turn it up very loud but when i turn it past 4 (with the gain on 9) the fuse blows after a few minutes of playing. I suspect its the output tubes im using, i salvaged them off something and im using them until i buy some el34s. What is the first thing i should check to make sure the amp isnt getting hurt?

[PRR]

Is there a number on that fuse? They are not all the same.

[HotBluePlates]

Make sure the output tubes fit snugly in their sockets.  Loose sockets (or the occasional JJ tube with skinny pins) could lead to the tube losing contact with pin 5 & bias.

[fossilshark]

Theyre 2 amp fuses. It could be the sockets

[sluckey]

Theyre 2 amp fuses. It could be the sockets

Does the amp require a slow or fast fuse?

[fossilshark]

Slow blow i beleive and thats what im using