Mike,
I know you've said that you checked the rotation of the impeller in an earlier thread, but to be honest, the consensus among all of those looking at your pictures, including the key folks at ClearVue Cyclones, is that the impeller is not rotating in the correct direction. Please realize we are not being critical -- we are trying to eliminate every possible cause of the poor performance you have observed. A relatively simple way to verify the actual rotation is to look through the clear sides of the blower side adjacent to the outlet and briefly run the cyclone so you can watch it's rotation as it spins back to a stop. The blades should rotate toward the blower outlet. If it does, then we are all wrong as to the cause. If it is rotating in the incorrect direction, there will still be exhaust flow, but it will be greatly reduced, creating the build-up in the inlet ramp as you've shown. You will then need to change the wiring connections at the motor junction box to reverse the motor rotation direction.
If the rotation is correct, then there is either a massive leak somewhere on the suction side or the impeller may not be keyed properly to the motor shaft and it is slipping under load. A thorough smoke test of the bin lid, the flex at the bin lid and any seams in the bin container (handles of galvanized waste barrels can leak.
Hope this helps.