We've had a lawn mower that, for the last two years, refused to run properly.
Well, when we pulled it out this year, it absolutely refused to run.
Deep cleaning of the carburetor insued.
Generic cleaning started. Nope.
Whoops, I didn't put the jet nut on properly. Somewhat, but nope.
Well, is the jet nozzle clogged? YEP!
Start? With a bit of starting fluid, ran for ~15 seconds.
Add starting fluid, put back on filter? Yep.
Five minutes later: S U C C E S S !
Whoops, some smoke coming off engine. Whoops, I added too much oil. Time to drain a little.