I removed my SME 3012R headshell from the arm at the rear of the table and noticed a bunch of dust on the cantilever and tiny wires around the coils of my vdh cartridge. I used a small, very soft painter's brush to carefully wipe away the dust. Tough because those vdh wires are so thin and everything is so exposed. The process was made much easier because of the removable headshell.
When finished, the cartridge looked brand new. I think the dust was from my Magic Eraser abrasive pad. I was quite surprised that the sound improved. I wonder if the dust on the coils really made such a difference or if simply removing the headshell from the armwand cleaned the contacts a bit. Regardless, sound improved.
I have never seen "hardened debris" on my cantilever. Only dust particles that are easily removed. The stylus is a different matter. The vdh stylus is radically different in size and shape from my MySonicLab and AirTight stylii. The latter two are much longer with a more defined shape and under magnification, they are much easier to view to confirm cleanliness.