B & S auto choke

[TKM]

I have a sears lawnmower with the Briggs and Stratton auto choke visiting the shop .I am having difficulty getting it to operate correctly If someone could help.
The issue started when the small return spring disappeared I purchased a new one and installed . Then the choke would not release choking the engine out . I sped the motor up slightly no effect . My neighbour felt the carb was dirty so I rebuilt the carb ,no effect . I removed the engine covering ,I was thinking some impediment on the choke arm linkage - nothing This takes me to the choke , it seemed to me a little limp . I changed that out ( a little pricey $ 32 Canadian) I centred it ensured it was facing the correct direction . No joy . This took me back to the replacement spring ,I stretched it . Now it starts chokes out a bit ,shut it off and restart and it operates without issue
What have I done wrong ? Anyone ?

 

[SmallEngineHead160]

Could you post Model type and code numbers for the engine?

 

[Rivets]

Also, take a couple of pictures of the carb without the air cleaner on and add the the numbers post. You may have to download them to your computer and downsize them so you can attach them to your post.

 

[TKM]

The mower went home a week ten days ago I installed a new choke - no joy .I stretched the return spring ,got some improvement . I then increased the RPM to about 3100 It now runs wwhat I think is satisfactory In all likelihood it didn’t need the new choke or stretching the spring Just an adjustment of the RPM
I do appreciate the replies