Because my filter doesn't seem to be catching all the debris it should, and its been some time since the sand has been replaced, I'm planning on Monday to change the sand in my Hayward 200 series filter. This filter has 24 screws in the midsection, can I empty the sand after i drain the water by removing that or must I go from the very top? Also, how will I know if the anything is broken or clogged inside without being able to see everything up close?