Depends how bad. Usually nothing a little contact cleaner can’t fix. It evaporates extremely fast. Just spray a little in there and work at it with a Q-tip, but be mindful that it doesn’t leave any cotton behind. Pipe cleaners would be ideal.

If it’s a mild case, you can even just use a patch cable/plug to work it between the contact points.

Do it in a well ventilated area and wear gloves, it dries your skin like nothing else. Read the can for other safety info. Good luck!

Use contact cleaner to clean it out; DeoxIT D5 is a classic suggestion, but I use WD-40's offering.