So, After alot of troubleshooting I have to ask pinside for some help.
We have a Who Dunnit at our pinball club, and it has had a very intermittent issue:
Sometimes, not always, when going over right inlane and/or outlane, it did not register and start taxi chase or free spin (when lit of course). Also the two taxi loop switches did not award a taxi letter when Taxi hurryup was activated always. In switch test everything is working, no sign of malfunction. After switch test, everything works for a while. Then suddenly after not playing for some time, it happens again. When I then manually push down or wriggle one of the switches, it works again.
I bought new rollove switches and diodes, and started replacing the tight inlane switch today. After that it seems to activate taxi chase and actually free spin outlane also all the time, consistent. But then the loop does not award taxi letter when taxi chase is enabled, no matter if you shoot from right or left. But it is alwats making the "VROOOM" car sound, just not awarding the letter.
Any idea? My current plan is just to replace both of the loop switches. But I wonder if it might also be some sort of matrice issue.