Another OHV with surging issues..

[Scrubcadet10]

3rd one this week....
104M02-0216-H1
Owner said it wouldn't start... he bought a briggs carb (From amazon) he said part number 594529,i looked it up and it appears to be the correct one. although everywhere i look it says NLA.
anyway, it fires right up. runs good until warm then starts surging... i've check for air leaks all around it. none. brand new fuel line... gas tank has good flow and volume... now here's the thing... when i tilt the mower up (handle end up, front of engine down) it stops surging and runs like normal, set it back down....runs good for about 5 seconds or so then starts surging. i have not pulled the carb off yet/.
Float level off?

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[hlw49]

594529 superseeds to 84001033 IPL shows the 594529 Used Before Code Date 18070100 and 84001033 Used After Code Date 18063000 but the 594529 superseed to the 8400103 They made a change in the main jet section and moved the main jet from the bottom of the pickup the the top so it would no become stopped up from sitting with fuel in the carb. At one time if you bought a carb they had the main jet section in the box and you had to change it out to move the main jet to the top of the main jet section.