Gentleman, I have a 1974 Ampeg V4b that has recently been giving me some problems when I turn the power on. It only takes a few seconds, but the switch goes back to the OFF position. I then try to put it back to the ON position, but it seems to resist and not make the connection. After some insistence on my part it will stay on. I'm worried about gigging with it and not being able to get it working during a set. Do you think this is switch related?(toggle type switch) If so, Are there exact factory replacements as I would like to keep it as original as possible. Thanks in advance.