I don't have a Jet Spin schematic, but Gottlieb has used resistors when a lamp is connected to 24V instead of 6V. They are usually 75 ohm / 10 watt.

That's what the Jet Spin schematic calls for too. Note that there is another, unrelated resistor (470 ohm, 2 watt) on the A/Alternating relay.

/Mark

Tuukka has it right.
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Note that this is for a 44 bulb. If you use a 47 it changes to 150/10. An LED cannot be used.

I have a Super Spin (2-player version of Jet Spin) and the schematic shows a 470-ohm resistor.

I checked on the game though and it is a 75-ohm, so schematic error. But I have had a #47 bulb in there for years and no problem. It is noticeably brighter than the left and right roto target lamps, though. These lamps only stay on momentarily when you hit the target, so that's probably why it hasn't burned out yet.

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Thank you currieddog and Pinside! I have a 77 Big hit that has been burning through “Special When Lit” lamps. They are on the 24v circuit with 75 ohm resistors. I could see they were burning a lot brighter than all the other lamps, so I checked the resistors and they are good at 75 ohms. The voltage at the socket however is 12v. A quick Pinside search found me this thread and the answer to my problem! I am using the 47 lamps instead of 44’s. Makes sense now.

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I’m all out of new 44’s, so I went through my used bulb stash and found a couple that still look fresh. Swapped them out and problem solved! It’s a good thing I’m not much of a player, those “Special When Lit” lamps don’t get lit too often when I play anyway.

Made a note on my schematic about the lamps. And the bottom of the playfield.