Speedo issue

Team 928 I have a 1986.5 that I am working on and having issues with the speedo springing to life at about 30-40 mph. I pulled the cluster and cleaned all the leads with deoxit but it’s still not working, I either have to tap the cluster and it will pop to life or it will kick in about 30-40mph. I’ve been following Dwayne’s instructions on rennlist but I’m at a point where I may be over my head. Before I start pulling the plastic circuit board I’m looking for any advice on other ideas as to why it would be doing this. Everything else on the cluster, including odometer, works great it’s just this jumpy speedo.

I have the wiring diagrams and I’m going to check continuity. Was hoping to test at least the speedo continuity from the cluster connection to the board. Also wondering if anyone recognizes my board, I wonder if I am missing a rivet (last one below the line of 3 in pics) Appreciate any advice! Thx!!!

The problem could reside inside the speedo assembly. If you have access to another assembly swap it out and see if the problem goes away.

For speedo and tach repairs, I've had good luck with

Dick's Speed-O-Tach
1900 N McClintock Dr, Unit C19,
Tempe, AZ 85281, United States
Phone: 480 994 9022