The filter crystalisation is not an 'old' filter problem, but a 'cheap' filter problem. Due to the type of glass substrate being exposed to the air, more expensive filters have dielectric coatings (or similar) that obviously push up the price.
Mine is the cheaper AAVSO version which does suffer from this, but it cleans off easily.
..bit of a lay view there, it's a known phenomenon to users of the Schott glasses and others too.
The solution is a solution: Balzers Plastic Polish
..btw Arne Henden gave _everyone_ a V filter lol