White debris on front of cartridge

Mold is an interesting hypothesis. I just assumed it was dried wet-cleaning agent that didn’t come off in the purified water rinse. I play a lot of vintage vinyl and god knows what the chain of custody these LPs had. I get the accumulation on the front of my retipped Supex SD 909. I would think the fine line stylus would create an environment ideal for breaking off deep groove debris 

My DS Audio DS003 also gets white "Schmutz" accumulation. I could give a Rat's Arse though..These Optical Cartridge Systems are the best thing to happen to the Audio Industry since the Birth of the CD 43 years ago !

So Dump all yer ancient tech MM's, MC, MI's, Strain Gauge Thingy's an just git yerself a DS Audio system of your budget.

Schmutz won't foul the operation of an optical cartridge?

Schmutz, as opposed to Peruvian Marching Powder, does tend to accumulate deep in grooves, whereas the latter tends to get removed by nasal vacuum. Stylus shape and arm geometry also.play their part in digging out deeply lodged schmutz while the electrostatic properies of the cartridge body ensure once collected, it stays collected. The latter potentially accounts for the difference between the Clearaudio and the Hana.

The Clearaudio Maestro V2 sounds like a good groove cleaner, maybe play the LPs a few times & see if the scmutz goes away.