Has anyone figured out what is broken with the 99 speedos? Is it the circuit board, speedo motor, what? I have one from an earlier legacy and the plug has 3 pins (vs the 5 pin with dark green wire) one black wire one white. Can this one be wired in?

you can find various fixes like improving ground connections on the flexible board described here but only a complete refluxing of all connections on the small rigid board the meter is mounted on seems to have worked for me (fingers crossed, 500mi so far). I first tried cleaning all the plug and edge connectors with electronic spray cleaner and the ground screws with abrasive plus an external ground connection. didn't help for me. I was inspired by ron917 who followed the same path!

Doogalbob on subaruoutback.org has a very specific repair to make to the PCB as well as full discussion of what can lead to a dead speedo.

Hey, I just fixed mine using the info from another thread on this site. just took the dashboard apart as the thread said and fixed the circuit board with a little solder. Easy and it works again. The speedo that is. I attached a picture of the fix.

The little blue wire is the fix as stated in the thread. The thread was called 99 speedo fix !