I have a Williams System 11B (Taxi) and two of the flashers do not work. Already tried new #89's and that's not the problem. I do not think it's a driver transistor issue either. The manual shows the "solenoid type" as "switched" for this transistor, which I assume means that something up/down stream of the transistor in circuit allows one transistor to control two flasher/solenoids on that circuit separately at any given time. In this situation it's Q25 and Q33. For those of you familiar with Taxi, the back glass PinBot and Drac flashers do not function. Per the manual however (see attached photo) Q25 and Q33 also control ball release and outhole kicker solenoids, and both of those work just fine. This means those driver transistors must be ok. Every other flasher/solenoid in the machine works fine.

So what else could be the problem and where do I begin to troubleshoot?

Thanks!

taxi (resized).jpg

Thanks, I will check for this and report back.

Reseated wire harnesses on interconnect board, swapped all new bulbs and it fixed the issue somehow. Thanks for the advice!