Clean the thermocouple with very fine grit sandpaper or emery cloth. I have done this many times with furnaces, stoves, water heaters, etc. You’re not going to hurt it. Secondly, a universal thermocouple for a gas oven “should” work, but sand the old one first, what have you got to lose. Emery cloth or 0000 grade steel wool is actually better than sandpaper. You can also test the thermocouple with a voltmeter, look up “how to…” on the internet.
Does it have a Type “?“ letter code on it? If so, match the type and you’re golden.