Willams Grand Prix Pinball Restoration

First problem: When the machine starts reseting the score reels it just continues to rotate the score motor forever. I understand from the guide at PinballHQ that this is due to the zero-reset switches not getting through to stop the score motor, but:

What is it that stops the score reels themselves at '0'? Cause if I put all score reels manually to 1, and then let the reset sequence start, they all count up to 6,7,8,9,and then 0, and stop there. So something is stopping them at 0, but the score motor keeps running, and the no 2/3 reset relays in the back cabinet keeps firering. Are there two separate mechanisms for stopping the actual reel at 0 and telling the motor it is at 0? Is that why there are two 0 reset switches?

Also, when i put the reels at 0, both of the 0 reset switches open, but one of them 'beeps' when i measure it with a MM. So basically it's closed all the time, even though it opens physically. Is this expected (has something to do with varying resistance?), or a short further down the line?

If anyone has any input on this, please use the comment field and let me know :)

See original RGP post here