Willams Grand Prix Pinball Restoration

I've had some progress with the machine, but I'm still having a major problem with the reset sequence. For some reason it won't complete. Here is what happenes after I manually trigger the Coin Relay (which triggers the reset sequence):

1. The score motor starts running (the blue box in the picture below)
   
   
   
   
2. The "No. 2/3/? Reset" relays in the backbox fires in a pattern with the two leftmost (red in the picture below) firering at the same time, alternating with the rightmost (yellow). This resets all the score wheels to 0000000 where they stop.
   
   
   
   
   
3. After a second or so, the Game Over Relay Latch is fired, and "Game Over" is no longer displayed in the back box. Instead the ball number and player up is lit. Player up is 1.
   
   
   
   
   
4. The Target Relay (on the playfield, next to one of the bonus steppers) is fired and locks
   
   
5. Both Bonus Steppers under the playfield locks the reset coil, and sporadically fire the step down coil (step to 0 because of the reset coil locked).
   
   
6. The two kickers to the left and right of the playfield fire and kick
   
   
7. The target relay is de-energized and the whole sequence from 4 is repeated.
   
   

I've opened and cleaned the two bonus steppers, and I'm fairly sure that the two player steppers (backbox and bottom cab) are zeroed. Same with ball count which displays 1. And all the score reels are zeroed. So it seems that everything is zeroed, but this is not passed on to the part supposed to stop all this noise :) Is this possible? Also, what has the Target Relay got to do with anything? Seems like it's firering in every little sequence I've tried.

If anyone has a clue why the machine is not reseting, please let me know in the comments! There is also a RGP post with the same topic here.