The key referred to is under the flywheel nut/washer.
Sometimes you can see the notch is not perfectly ligned up
with the slot. The key breaks away and advances the timing. Usually, this is felt as a slight kickback in your hand when pulling the start cord.
Also, as I mentioned earlier, make sure the head bolts and tight.
I have had several here that were given up on and it was just loose head bolts.
I make it a habit of checking them first, spark next, and then gas.