Manual choke and manual spark advance
My 1927 Willys Whippet has both a manual choke and manual spark advance, both cables operate through knobs on the dash. The car runs best with both pushed all the way in. However, as I drive along, both the choke and spark advance knobs slowly start to slide out, on their own, causing the car to sputter and lose power. I find myself having to push the knobs back in every couple of minutes as I am driving. There must be a way to fix this.
You can see the choke knob to the right of the wheel
Adding a return spring comes to mind. But you want to be able to adjust the cable and lock it in place. Since this is a common need there have been some manufactured. You can replace the existing cable with one of these locking cables and your all set. Measure the length of the cable you have. If it is 72″ or less you can get away with this stylish design for under $50.
Adjustable Locking Cable
Or this one for under $15 I found on ebay;