Two piston preset pilot lamps were burned out (Great manual #2 and #4), so I decided to go ahead replace all 17 at once. It’s a good thing I did, because the wire leads were very corroded and probably wouldn’t have lasted much longer. The old bulbs had wire leads coming out the sides, whereas the new bulbs (#2102) had leads coming out the bottom. I also coated the wire leads with WD-40 to help protect against future corrosion, and installed them a little higher off the circuit board to bring them closer to the jewels (and hopefully make them shine a little brighter than the old ones.) While the bulbs were out I went ahead and removed the jewels to polish them and remove as much rust as I could. I was very pleased with the results!