yep - I would say buildup too. There's lots of diff ways to get rid of build-up. The first step is to strip. You can do several HOT HOT HOT washes with or without a squirt of dawn. peek in the washer and ck for bubbles, when you don't see anymore you've stripped them clean. Some people use baking soda and TTO once they're stripped...search for no-detergent. SEEPAE did a little experiment on this I believe. Do you use liquid or powder? I use FBs a lot and I found that liquid caused more buildup and repelling. I'm using sportswash now but will prob switch to powder when it runs out. HTH