I have been working to get a '27 TT running for the past few months. After a few setbacks (including a bout of Siatica - glad that's over), I installed the battery.
Earlier I had rebuilt the bendix, and today I decided to see if it works. So after hooking up the battery, I opened the hood so I could see the fan, turned the key and stepped on the starter. Nothing. Turned off the key. All of a sudden, the engine started to turn. Took foot of starter and it kept turning. And the starter switch started to smoke! Quickly disconnected the battery switch.
Ordered a new switch from Langs.

So, question: The starter switch is removed from under the car? It appears on of the nuts is under the body. More work.

Had similar experience with replacement imported starter footswitch, that when used the third time welded itself together on contacts and could not release. The only quick way to stop the starter from turning was to disconnect the battery at the negative terminal. I strongly believe that you do not have a factory Ford foot starter switch in your car.

They are rebuildable. If yours has tabs, they need to be annealed before bending. If it has two screws, no problem. Most of the time if the contacts aren't too pitted you can file them and reuse.

Just one of the reasons I have a battery disconnect switch. Just in case.

I use a solenoid so the starter switch only has a little current going through it. Let the solenoid take the heavy hit.

Steve, I also use a solenoid fired by a modern replacement foot switch. Worked great until one day it stuck closed. I then used my battery disconnect switch.

That foot switch got some corrosion inside and stuck on. The effect was the same as a stock switch welding closed! I had to disconnect a wire and hand crank to get home.

I was able to wire brush the parts and correct the problem.

Solenoid and disconnect switch: belt and suspenders! ... keeps you from getting caught with your pants down!

TH