Another possible solution (although still requires the memory banks to retain) might be to take a fine-toothed file and make a few passes along the metal rim of the jack (the flat area the male jack extends from) on three or four sides, so you could feel the difference even in a bad lighting situation. If you don't have a jack with the metal rim exposed, a zip tie cinched down (tail trimmed as flush as desired) just above the jack housing could also provide both visual and tactile reference. Good luck.
Cheers,
Lee