I was just doing some routine maintenance on my Boss 5 Series 1. I have always had a little trouble with transistors popping occasionally. Once a month or so. I even went to all new MJ series transistors and all new 1N4003 diodes but it did not seem to change anything. Not a big problem as I keep a 10 pack at all times and could probably change one in the dark. I have been trying to tune up the machine a little. New oilers, 1 new(er) superior motor etc. I was just checking the SMS board for current dropout as Machinetek had mentioned in a post. The E-stop does work in this machine and I have used it. The ODD issue here is that when you hit the E-stop the current does not drop at all. Thru much time in the manual and some hair pulling I found a little non-Bridgeport wiring on the CR-1 at the #135 wire. I removed the wire and the current will drop to about .5A and then decay slowly. This machine has always been a little quirky on the limit switch but has always seemed to work. George, do you think this could be causing the occasional transistor blowing? I think the 135 goes to the E-stop and then to the 39 which is the 24V ground(I think)?. Anyone have any suggestions? thanks.