This looks exactly like the BK Precision PR-60 and the Agilent N2791A probes. And same 25MHz, 700V spec and everything (it ain't Agilent nor Lecroy, would BK be the OEM?
). In case you find service manuals for those or something. I do have the BK precision one, may open and see if they sanded off the chip ids. Looking at yours, almost certain they did though...