I had an almost identical problem with a new DLE 55RA. Full choke on, the engine would bark with about 10 flips of the prop. Choke off and I could flip the prop all day and it wouldn't even bark or start. Put the choke on full again, engine would bark after a few flips of the prop, choke off and no amount of flipping the prop would the engine bark or start. So I did a little experimenting and after the engine barked on full choke I opened the choke between 1/4 & 1/2 open, just a few flips of the prop the engine started and run. It idled well and I had no problem going to full power at factory needle settings. I removed the carb and opened the pump side of the carb and inspected the pump diaphragm, it looked OK, it was soft and pliable just like new. As a precaution I replaced the pump diaphragm. I put the carb back on the engine, went through the start procedure again, choke on, roughly 10 flips of the prop the engine barked, choke fully open, flip the prop 3 or 4 times and the engine starts and runs as advertised. As far as I could figure out the two small flapper valves on the pump diaphragm were defective and not doing the job they were designed to do.

Roger