Are they the same bulbs? If they are.....I would just put the same (new ) ones in. Probably just dim from being worn out. Can you clean the inside of the lenses ? (q-tip?)
Incandescent bulbs do dim over time so replacing them will brighten the indicators but replacing them with LED's is a better option "in MY opinion." To each their own.
But as mentioned about the lenses, at 10+ years old maybe the contacts are dirty. Isopropyl alcohol on a qtip should clean that.