I picked up some powdered Citric Acid from Mountain Rose herbs along with four ounces of menthol crystals. I haven't used any of the acid in a mix yet, but I did put a couple of hefty tablespoons worth in a pot of water/vinegar bath to boil clean some attys with. 5 minute boil and they vape and look like new.
I now have enough menthol crystals for two lifetimes. 4 ounces for $10
and 1lb. of powdered citirc acid was $3.50
Mountain Rose Herbs | Bulk organic herbs, spices & essential oils
The powered citric acid and vinegar bath sounds interesting. I may have to try this on a couple of old 901 attys. They aren't quite dead yet but they are 3 1/2 months old. The only cleaning I've done was forcing hot water through them about once a week. That seemed to keep them going for a good while but now they're on their last leg. Could be just their time to go... But think I'm still going to try this.