Craftsman 6.0 Gold with B/S Engine Not Starting
I have a Craftsman 6.0 Gold mower Model 917.387400 with a B/S engine. Not sure of the age, and I don't have any manuals for it.
I started the season a couple of weeks ago with a new air filter and new Champion 5861 Spark Plug gapped to about .028-.030. This is the same plug that was in the mower last year.
The mower suddenly decided to not start the other day when I stopped cutting grass to take a bathroom break and refill it with more gas. Earlier in the day it had been running fine. When starting hot/cold I've always kept the throttle bar pulled to full open and pressed the fuel plunger 6-8 times.
Despite multiple pulls, it wouldn't start. The plug did have gas on it, though it was hard to check spark in the bright sunlight.
Everything I see online seems to indicate cleaning the carb will cure many ills, but my past experience with cars, trucks and motorcycles reminds me that most "carburetor" issues are actually electrical.
There is a choke or other spring loaded assembly on the top of the carb that can be self adjusted that I've never touched. Picture attached. Is there a certain position the linkage should be in?
Past that, are there any common issues with these engines that I should be aware of that may be causing the no-start problem?