Eric (and anyone else), about ground leads for the P612x probes:
As I said, these are hard to come by (in my experience. If anybody knows of a source for new stock on these, I'd be happy to know about it), but I'm doing a little experiment in make my own.
I ordered a set of crimping connectors for 2.54mm pin headers and I have tested them against a partly disassembled ground collar from a subminiature modular probe (part number 343-1003-01) which, I think, uses the same kind of ground lead as the P612x probes. The female crimp connectors seem to mate correctly with the pin in the ground collar.
The ground leads for the subminiature modular probes are part numbers 196-3286-00 and 196-3287-00, 8- and 12-inch, with the alligator clip either permanently attached or screw-on, respectively. The ground leads for the miniature modular probes are different part numbers, 175-0848-00 and 175-0848-01 for 3-inch and 5-inch respectively, but they seem to be interchangeable in my experience.
I'm currently waiting on a set of crimping alligator clips, and selection of wire gauges for making my own ground leads, and will report back after those arrive.
-- Jeff Dutky