Buy an emission tester which will give you a good indication of how much life is left in the tubes.
how to test tubes with your multimeter(filament continuity)
G'Day all. My last post was concerning a bad fuse or bad tube. I borrowed a tester but I'm not confident in its reliability due to inconsistent readings. There are no tube testers in the area. So what to do? I found this video about using a multi meter for testing. I'm sure it will not tell the whole story about the tube. I get the idea that that a tube with continuity may still be bad but will not cause catastrophic damage to the amp that it is inserted in. Am I on the right track? Is this test of any real value? Or is it a waste of time? Thanks