We did have these beasts a while ago there was a bit of a problem especially around curved corners in the plastic moulding. We traced it to use of incorrect cleaning agents causing the plastic to breakdown.
We filled the cracks with plastic filler and rubbed the finish down so you couldnt see it and changed the cleaning regime to a recommended one.
Some of the agents especially those containing alcohol of bleach can be to strong for the plastic bases used on. Or applied to vigerously.
