Phil, a "non-car guy" friend of mine lost his Dad 2 years ago and is finally getting around to cleaning up his Dad's stuff. Apparently his Dad was somewhat of a car guy, maybe 40+ years ago. Phil gave me a bunch of tune up tools in unknown condition. Most of them I've already discarded as busted or passed on to other friends when they were duplicates of mine. I've been around electronics since Uncle Sugar educated me on fixing autopilots and heading systems on B-52s in 1966. I know how to run an oscilloscope for general electronic troubleshooting and used then until retiring from Hewlett-Packard last year. This one has me puzzled. https://talk.classicparts.com/photos/data/500/medium/scope.jpg https://talk.classicparts.com/photos/data/500/medium/DSCF00033.JPG It seems to work. I can get a nice high voltage trace when connected to my GMC. But I don't understand how to use most of the functions shown on the various switch positions. I understand what the function means, just not how to interpret that function on the screen. I've searched the web using the Sears number 244.2135 on the label on the rear of the unit and only got a hit on one for sale without the test leads in France. Any chance one of you has a beast like this or more importantly an instruction manual for it?