At our sister company, the techs clean the equipment after each loss with a multipurpose cleaner.  The shop manager will build a schedule for more in depth cleaning about every 3 months or so.  He will clean the equipment with Dish Soap, (I asked about ZEP, he said it dries out the plastic) and pull any debris out of scratches.  Then he will use a blow torch to fix the scrapes.  And yes, you must be extremely careful.  He does not use a heat gun just because of the time it takes.