I bought a red Yamaha BB300 off of ebay back in January. So far I really like the bass but the tone pot is not working correctly. At least I don't think it does. When I adjust the tone knob I hear no change in the tone. When I play, it just doesn't have a lot of punch to it at all. Shortly after getting it, I took the bass to GC to have it set up properly and replace the strings, and I told the tech about the tone pot. But when I picked the bass up after everything was done the tech said that the tone pot was working properly. He even demonstrated for me, as my bass was plugged into an amp (I forgot what brand it was now), but he adjusted the tone and I could hear the difference. I was stunned! I have a Peavey Max 115II amp that I bought brand new over a year ago from GC and I can hear no difference in tone when my Yamaha bass is plugged into it. However, I CAN hear a difference when adjusting the tone on my Fender MIM Standard Jazz Bass. So what is the problem?