I have a few questions, here are pictures of two AR-4x woofers. The one with the smaller magnet is like the ones in my 4x's. The larger one, I saw on ebay. Why was there this magnet change? Also, I was thinking about replacing the pots in my 4x's, or cleaning the old ones. I would really like to keep the old ones. Is there anyone here who has the tools to clean the old ones?