DG , I checked the float level and its correct.
I pulled the pump and discovered there was a lot of rust stuck to the leather. I cleaned that off , thinking that maybe the fuel was leaking back past the seal where the bits of rust were.
Then I saw a Zenith carb on a spare engine in the shed and decided to try that out , It works great , no more flat spot and no leaking , so if it is as economical to run, I will probably just keep it on the truck.
Then I got carried away and fitted the cleaned up carter to the spare engine , thinking I will give it a test run next weekend , just to see if the engine is ok. (its been sitting for 20yrs)

Just as well we do this for fun , eh.