Damn.....that's a bit of bad news especially after being so careful in looking after the Volk's.
I hope you find a cure without going through the expense of a refurb.
If all else fails, before you go for a refurb you could try those impregnated sponges that JML and the like sell. I used some on my neighbours car where Chipsaway oversprayed a panel trapping dust underneath too!
I have read similar stories on how fragile the lips are on my LMGT4's.
So much so, for the past 5 years I only clean them with a running hose and a MF cloth.
Then every couple months use a sealant with built in cleansers to remove any ingrained dirt and add protection.
Good luck Chris.