I've got a Snapper rer in with a Briggs engine...M-219907, T-0131-E1, C-041123ZA. When starting, if you move the throttle to choke...the choke closes just fine, however, when you pull the throttle back to run, the choke is very sluggish about opening up, in fact it only partially opens. Isn't there supposed to be a return spring on it somewhere? I've looked at an IPL of the engine but it dosen't show one.

 

Yes there is a choke return spring. It coils around the choke shaft. Depending on how old the mower is, the spring is most likely broken. Choke shaft needs to be removed to replace the spring. Spring number for a Walbro 690802 for Nikki 698779.

 

This is a common problem with the walbro and nikki carbs used today. Remove the piece at the end of the carb so you can see the choke. Grab the choke plate with pliers and pull it out. The choke shaft will then slide upwards and out of the carb. Do not lose the spring, or forget how it attached. Then, take a razor blade and scrape the choke shaft. You'll get tiny shavings. Go all the way around the shaft, making sure you get the areas that contact the bushing area in the carb. Then reinstall it and check operation. If it still sticks, shave it a little more.