I checked the fuses in my four P90 probes (1x) to ensure they are 100ma fast blow 3AG glass types,
and sorted one which wasn't performing consistently, and had the issue pictured,
semi-hidden, hard to spot cracked solder joints
Removed the fuse first, in case I cooked it, then a solder refresh just enough to do the cracked sides only, and good as new.
Multimeter reads about 33 to 37 Ohms for any of the 4 probes, which is the 100ma fuse impedance (and a quick way to check rather than disassemble)
The P91 probes (10x) are next, best left for another day asap,
...perhaps a more fiddly job you need 4 hands (and two brains?) to assemble