Take the motor off. Pull impeller and shift out. If there is any crud in the motor housing, or on the impeller or shaft, that can stop it dead. If messed up, look into an aqueous quite flow 55/75. I have had both the 110 and 55/75. The 55/75 is much more efficient and a lot more dependable than the 110, in my experience. Just be careful with fine substrate or sand. And that goes with both filters. The 110 has way to much water bypass anyways. Yes, I am against any hagen products. But that is due to experience and lack of customer service and product support. Fluval and aquaclear both will not honor product warranty. And that is from personal experience. The 55/75 is half the cost, and, if u can think outside the box, just as customizable as the 110.