Hi Rhodes,
The safest way to clean the terminals is to remove them and soak them in white vinegar and polish them with very fine sandpaper. 400 or even 800 wet-dry sandpaper used for car paint works well.
If they cannot be removed, then you can still used the vinegar but with a Q-tip, making sure none gets into the camera through cracks and openings. It really depends on the extent of the corrosion.
I don't know the 124G but this is a common problem I've faced with a couple of m old cameras.
David