It seems i have some rust in my heat core. I stuck a couple Q-Tips down it and brought them back up wiht a lot of residue. I flushed it out with a lot of really hot water and its still in there. I let some water sit in their for bout 10 min then poured it out and there was no discoloration in the water, it still looked like pure h20. Should i worry about this? and is there any good ideas you guys have to clean this out?