Part of tube (valve) guitar amp maintenance is changing out / replacing the tubes (valves) when needed, but there is no need to take it to a guitar tech. Simple order a matched set of power tubes and a preamp tubes swap them in yourself. In this video I show how to swap out the tubes in a Fender Bassbreaker 15 tube amp. The process is more or less the same for any tube amp. Whether your amp is a Fender, Marshall, Vox, Mesa, Bogner, Orange, Bad Cat, Matchless, etc... It's pretty easy do do. The same process is for every tube amp that I know of, no matter what kind of tubes or valves your amp uses; 6L6, 6V6, EL34, EL84, KT88, 12AX7, 12AU7, ECC83, 12AT7, AU4, etc...
I also talk about a few misconceptions regarding tubes, like "Don't touch them with your fingers or they will explode!" Is that true? Watch to find out.