I’m presently going through a Space Mission. I found that the match unit was gunked up and stuck. Unfortunately, it doesn’t have a separate Jones plug for easy removal. But I cleaned the inside gears and also the outer printed circuit boards with a toothbrush dipped in 91% isopropyl alcohol, then lubed the circuit boards with Super Lube, and it mechanically works now.

I concur. The unit does more than simply control the number match. It also contains an alternating switch that impacts gameplay. I recently purchased a Rancho that lacks the alternating switch cam in the match unit. I haven’t gone through that machine yet, but the alternating switch is important enough that I have also bought a used match unit that was on eBay so I can have that cam.