The Stovebolt Site Forums The Shop Area Engine Shop distributor 'knocking' after points replacing

I just replaced the points, rotor, and condenser on my '53
Chevy 3600 216 c.i. engine (which I have done at least 30 times in my 35 years of owning it). This time however there is a distinct knocking sound like something is hitting inside or below the distributor when it is running. It started right up but the noise was not normal. I opened the cap and all looked good, I reseated the rotor and it seated on the tab like it should. I did notice when I pull up on the distributor while the engine is running the sound almost completely goes away. When I push down slightly it gets louder and I can feel like something is hitting something when it is running. Any ideas?