Hola,
Sometimes I had a bad position where the coil of the woofer scratches the magnet. Just moving the woofer position did fix the problem. The top now is at the bottom. Do this on both woofers. Also, I had a loose cable touching the woofer's cone. This gave a really annoying bass sound. Just check this for the woofers.
Regarding the stats, all the surface area of the diaphragm should produce sound. If you have certain parts of the stat panel dead, you have to replace the panel. If you have dull sound, with the aid of a good shower might bring them back. The disassembly procedure is about the same as it is with the shower cleaning procedure.
Happy listening!