Had the same thing happen to me - I got rid of the COOL hubs and went to grease and no problems since.
The COOL hubs are made by UFP - they have a TN location that ships parts out pretty quick and is far cheaper to buy from than a dealer.
Call Dennis at UFP...800-835-9211 ext. 16, he should be able to hook you up...
It's not hard at all to work on trailer brakes - Dennis can tell you what you need to do over the phone and save you some serious coin.