[Electrothaumaturgist]

Yes, cleaning the push button contacts is a great idea. However, when I got the 42-400 first running, I could only manually tune it in- no push button action. So, I played with it awhile, and found the oscillator coil had a bad (loose) wire going into the center of that coil. (The wire was frayed going over the top of that coil, and only one strand of the outside wire was making contact with the center wire). I was able to drip one small drop of solder on it and "catch" that single fine wire in the center from the lead. Can't hurt to check that coil. (Be extremely careful when checking that, though-very delicate). Also, check that all your tubes are lit- jiggle the xxl and xxfm tubes and and wait a few seconds to see if that helps. (Sometimes the contacts at the tube bases are dirty). Good luck.