That's right, flatlinerz. Those engines will not start in winter without full choke, so that is at least one thing that has to be fixed. Please clarify, though: when you lift the tab, it should move up until the black bellcrank on the carburetor has moved all the way anticlockwise, but the tab should not move all the way to the top of its slot. If it went right to the top of the slot, there would be something wrong with the wire link between the bellcrank on the governor plate, and the bellcrank on the choke.

So, the choke is not closing, due to the speed control cable inner not moving far enough when in the choke position. There are two ways to adjust it. The preferred way is to lengthen the cable outer, by adjusting these nuts at the speed control lever on the handlebar:
[Linked Image]

Please post a picture of the same part of your mower, so we can assess whether it has enough remaining adjustment to fix the problem. If it does not, we'll have to resort to the non-preferred approach.