I just pulled out my cartidge to clean the filter, and it looks like the core broke off at the bottom. The bottom of the core is stuck in the bottom of the canister....I mean stuck! I hosed down the filter and put it and the core it's still wrapped around back in and turned the pump back on, but I'm pretty sure I need a new core. Has this ever happened to anyone, and if so how do I get that stuck core bottom out of the canister? Thank you very much for any replies in advance.