Seal
I've seen the pulley with a deep groove that would not seal because it was so deep. My buddy found a kit to repair it. It was basically a piece of thin steel tubing that fit snugly over the damper snout. It was a SBC. Don't know where to find it at this time. This was way back in the 70's. If that is the problem, I'll see if I can find the kit if you want it.