I have a 5.0Hp Tescumsch on an old Agway snow thrower. It went in for repairs as it would not start. I recently got it back and was told on pick up it starts on the first pull. It did the first storm. The next storm it took a good 20 minutes of pulling and then it ran rough but I got the driveway done. The next storm I was forced to shovel as it refused to start no matter what I did.When I was all done I took a good look at the snow thrower and noticed that the ignition key is missing (the key located under the idle and choke). My question will this missing key prevent it from starting? Can you get it started with out the key and if so will it damage the engine? I have no idea if it was missing when it was running rough.

If it the was a plastic key , you can stick the handle of a plastic fork or spoon ,or something to break contact, not metal.
If it was a metal key uplug the wire from switch