Leaf Blower runs on choke?

Hi,

Hope you can help with my older Briggs, Little Wonder leaf blower. Model # 9005PD
Engine #130202 1670-01 code 87012907

It starts and runs fine for maybe 10 minutes, then dies.
I find, if I move the run lever halfway towards choke, it again runs normally for 5 min. and then dies. I then have to push the lever towards choke then back halfway and I get another 5 min. of running time. It continues this way until I shut it off.

I found the head gasket was loose, now tightened.
I changed the plug.
Air filter is new.
Maintained seasonally.
Fresh gas.

I did find a small gas leak at the gasket where the carb sits on the gas can.
Screws are tight, yet gas is present.

No other problems are apparent.

Have any suggestions?

Val