This is a B&S Gold 6.75 torque 190cc engine on a Craftsman mower. Pulled the mower out for a first cut and it won't start. Was stored with empty tank. Changed the oil and cleaned the air filter prior to attempt. Tested for spark - good. Tested for compression - good. Loosen the bolt on the bottom of the fuel bowl and fuel comes out. Removed carb and cleaned every port by running a wire through then spraying with carb cleaner then compressed air. Yes the meter jet ports on the bolt on the bottom of the bowl too. Attempted to start and nothing. Sat for a day then removed and cleaned carb again and this time testing float needle seat by blowing in fuel tube. Restricted flow with bowl down. No flow with bowl upside down. Needle and seat good. Sat for three days, pulled the cord and it started right up and ran strong for 20 seconds then died. Back to no starting. What am I missing here?

I am considering a string trimmer dethatcher attachment for my 4000 sq ft lawn every couple of years and would like to get input on how well they work from those that have experience with them. This is a Troy/MTD attachment that looks very similar to the Honda and Mantis design/construction with three rows of spring tines per side. This will be paired with my several year old split boom 32 cc Craftsman/MTD trimmer, which has pretty good power. I don't expect this attachment to be as good as a pro walk-behind unit, but it should be able to do a decent job. The pro equipment is out my price range. My other option is a GreenWorks walk-behind electric, which doesn't look all that durable. The lawn services around here get about $300 for a dethatching, so I'd like to invest in a piece of equipment if possible.