Thank you all for your help on repairing my 5100B. I am totally blown away by your willingness to help and your knowledge! I am really green with this instrument and appreciate your input. I now have replacement part numbers as well as a way to determine what the values should be. Thanks to all! I'll order the parts this evening and keep you posted as to my progress. Again, really, thanks to all who responded! Best regards, Dave SmithW6TE *********************************