That is one of the oddest ideas I've ever run across. Someone was thinking about diagnostics, sorta kinda, back in the '60s! Of course, unless the machine came from the factory with a built-in diagnostic harness (which I doubt), it probably would have taken longer to hook this gadget up than it would have to just operate the machine with the timer and figure it out from that.
At $10, I may just have to bid on this thing! If no one else here is going to bid, I'll go for it. (But if someone is, say so, and I won't bid against you. I just want to make sure it gets saved.)