The first pump quit after 300 miles, the second one wouldn't pump straight from the box. Just like yours, the second one "looked" like a good quality unit. That's the one in the photo with the silver top. The gold top one is the 300 miler with the pump arm that was riveted together improperly by the slave laborers.
Take a look at my cam lobe with the varnish and shiny streak and then look at the arm of the pump that worked for a short time. The shiny part of the cam is where the thin part of the pump arm rode. The rest of it is varnished up because the arm made no contact there.
The pump arm only made contact on 1/16" of an inch on the cam instead of the full width of the arm. They are absolute Chinese garbage from the get go and will not work and cannot be made to work.
The pump arms are too short or the throw is incorrect or something but trust me, your cam is not worn out.
The original pump was rebuilt and I've put over 4000 miles on it in the last year.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)