You lucky beggar! Hey! Didn't I say that when you announced the find? My memory must be going. Get the technical manuals from Tek - "Technical Data" and "Parts List and Schematics". Expensive - expect to pay $300 the pair - but worth it. Invaluable for repairs, and I have had to do several of those since I got my machine (mostly PSU failures). I can get you part numbers for the manuals if this will help. 4054A is the nicest of the 4050 series. 4054 has the large screen and A signifies faster GPIB and extended BASIC... Philip.