Interesting information from Analog Planet on Stylus Cleaner Onzow Zero Dust.

When I was with the Garrott Bros many years ago they showed me on an electron microscope the crap in most cartridges in for repair -

The most common and worst 2 problems were minute pieces of carbon fiber from either record or stylus brushes and gunk and residue from excessive use of fluids that would wick its up the cantilever and gum up the works - worst was Stylast & First.

worst was Stylast & First.

You could tell under the microscope what fluid it was?

No we had test samples

Atomic absorption will tell you also as well mass spectrometry.

we use it a lot doing analysis on fluids. 

@dover 

Yes, I can believe that about fluid residue. Before I had my Koetsu photomicrographed, I cleaned it with 95% pure ethanol. 40 hours later the pump on the electron microscope couldn't pull a sufficient vacuum because of off-gassing - and the only possibility, which I was assured was quite possible, was the alcohol.