I'm in the middle of some repair work on an older Heathkit O-Scope model IO-102, the vertical board uses an N-Channel FET (Q1 - EL131 - Heathkit part number 417-241) which has become very thermal. I picked up a replacement doesn't work in the circuit. (NTE cross shows an NTE133 as the cross for the EL131). I've tried a couple NTE133s and an MPF105 as well, all work the same in the circuit but don't work correctly. Does anyone know of an exact EL131 replacement, know if the ECG312 really is a good replacement or even better know where I can get a Heathkit replacement part. Digikey, Mouser etc. all don't recognize the EL131 part number. Thanks -Neil