Bolens Trimer Wont Start

I got a Bolens Trimer BL250. I replaced all fuel lines, Filter. Fresh fuel with correct fuel/oil mixture and Carburator but the only way I get it to start is to put a few drops of gas in the combustion chamber then put the spark plug back in and it fires right up. Once the engine is hot I can start it up with no problem and it runs non stop but once the engine cools it wont start unless I do the same procedure. What Maintance steps am I missing or need to do.

Bolens Trimer Wont Start