First, some basics. The engine was built on 26 February, 2006. I think the last number in the Code is probably spurious and it should read 06022651. The plant which manufactured it is given as 51. Plant 51 seems to be an administrative center (identified as "TBS") at Briggs headquarters at Wauwatosa, Wisconsin, so I suspect you have an early production Chongqing engine. For one reason or another, Briggs does not seem to ever stamp the actual number for Chongqing (Plant 28) on engines made there for export. So far, they all seem to have Wauwatosa admin center numbers.

Here is the Illustrated Parts List:
http://bsintek.basco.com/BriggsDocumentDisplay/18hszLXAnfBhU7y.pdf

Here is the Operator's Manual:
http://bsintek.basco.com/BriggsDocumentDisplay/msvtDR-K_ny7tH217FzoPu.pdf

You haven't posted a picture of the engine, but it seems to have a PulsaPrime carburetor as the only option. If yours does not have a primer, please say so.

Now, to the nitty gritty. The cover of the valve chest is also the crankcase breather valve, so it needs to be clean and clear. It has a flat phenolic/fibre flap valve held closed by a spring, which opens momentarily each time the piston moves down the bore. If it is clean, and the valve is not stuck, all should be well.

Because you have a primer carburetor, and those primers are rather prone to not working, one possible cause of not starting, is not having any cold starting enrichment. I suggest you put a small amount of petrol into the cylinder through the spark plug hole, and see if it then starts. If it does, your problem may be an inoperative primer.