Reassemble and check
With the worm off (Important ! ), reassemble the axis and tighten the clutch knob. The axis should turn freely and without binding. This is also how to check the axis for binding initially.
If the clutch is not tightened, you're not simulating the operational condition. With the clutch knob loose, the axis may turn freely. But tightened, binding occurs from the misaligned worm gear and bearings caused by the improperly seated bearing cap.