Once assembled I tested each score reel by starting a game.
Checking they reset properly and score properly including advancing the adjacent reel once passing through the "9".
One of the reels did have one of these issues and although it would reset ok it would not score.
This turned out to be the eos switch on the coil not opening properly when the coil was activated.
This was caused by the end stop for the switch being to tight on the switch and the tension to high on the other side of the switch.
I had noticed the stop bent away (you can see this in my before photo) while dismantling the reel so I straightened it, turns out I straightened it too much.
A small adjustment and it worked immediately. There was one concern with this and that was that because the switch did not open at the eos then coil remained on, causing it to get hot, luckily no damage was done.

One of the reels was not advancing the adjacent reel, there are two switches that perform this function the "9" switch and the N/O switch that is activated but the reel actuator.
In this case it ended up being a dirty "9" switch that was easily recitifed by running some cardboard through it.