Cleaned the lens with methylated spirits, appears to have removed all fungus, though minor marks remain from the solvent. I'll try cleaning this again at a later date as the lens disassembly was much easier than I thought it would be.
Metho is not a good cleaner for that very reason. Doesn't Metho have stuff in it to prevent people drinking it? Isopropyl is better and commonly used to clean lenses.