That could be feasible but more work than I was hoping for. Actually, that might make for an improved tool though if a way to mix the two channels was used.
I hadn't thought about that. I've repaired several of the old probes, back when you could still buy parts. The most common problem was a shattered crystal. The probe was spring loaded against the crystal but I have no idea how HP compensated for the effect. There was a preamplifier inside the tube for the probe. I'll have to see if the manuals had the schematic for that circuit. It may give some clues.