choke not engaging!

Unscrew the lock nut, and inspect. Poor fuels or debris can foul it up, and if any debris is present, it went into your motor as well.

I have had this happen and inside the small rubber booton the choke shaft there are 4 plastic ratchet teeth and these had worn or lost there tension or both. I managed to fix it with some tie wire to put tension back into the lockers. It lasted a couple of years but eventually a new (and quite expensive at the time ) choke unit had to be fitted