The engine's manufacture date was 15 December, 2010, so it is a very long way from being an early production unit. If you dismantle the engine, it will be interesting to see what has gone wrong with the valve gear.
Here is the illustrated parts list:
http://bsintek.basco.com/BriggsDocumentDisplay/18mnBGXPnfBhU7y.pdfHere is the operator's manual:
http://bsintek.basco.com/BriggsDocumentDisplay/ioqsAJJU0HDjhJvcv4.pdfIf you are going to work on that Intek, you might need the workshop manual. It can be found in the subscriptions area:
https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=20019#Post20019The file you need is called B&S 276781 Intek Single Cylinder OHV.pdf
(276781 is the Briggs part number for that manual.)