Key falls out of wafer lock

[8550jim]

My brother has a gasoline powered welder that uses a simple wafer type lock. The problem is that the key will fall out due to vibration when it is running. Also, the key has to be pushed in a bit to turn it. It seems to be very sloppy. He has tried the spare key that has almost never been used and it is the same. My question is, is this caused by worn wafers or must the cylinder or entire lock be replaced. The key has cuts on both sides if that helps. Thanks

[Kaesekopf]

Didn't see this earlier

Without pictures of the key, from your description I'm going to guess that the max cuts are toward the end of the key and that the ridges between cuts are worn down. If you can find a blank you could cut one with ridges to hold the key, or perhaps a locksmith could help you out