I always start my V15 with an empty bin and clear airway. But lately, after it has sucked up debris and lots of dog hair for about 15 minutes the bin is empty and the airway is blocked. The blockage is always in the internal passage and I am able to finger all the debris out through the hole on the side. A visual inspection through the passage gives me the all-clear. Then 15 minutes later - same thing - nothing in the bin and all in the airway. I have washed, rinsed and dried the filter - still with the same result. What now? Also lately, the bin will come off just by moving the red lid lever down. Could air be going in past the rubber seal, thus losing the air vacuum?