[Eric]

Have you cleaned the tube sockets? Take a real close look at the tuner for dirt or dust balls down deep, I like to use a flashlight and a hand lens. Good luck David 

I have cleaned the tube pins knowing that locktals can have a problem with corrosion but you can usually hear the difference when you wiggle each tube with the set on. On the Tuner I have cleaned and checked the plates and at the shaft making sure there is no trash bridging the segments, As a side note I have one of those magnifier visor, best thing I ever bought leaves your hands free!

May have found the problem it is the trimmer on the tuner will run it for a few days to see it that is what it is.