I picked up the 504, and yes, also picked up a pulse amplifier. Paramount makes a nice replacement amplifier that is less expensive and im sure works just fine, but I wanted the real thing. I was in Paramounts shop, and its like a Candy store for these machines. He is restoring several machines and cabinets. id bet he had 10-12 for sale that had been re-screen printed and painted to like new appearance. I went with an original paint machine with a restored cabinet. His shop is like a hospital operating room, and this guy knows his machines. If you need parts and service, he,s the go to.