Gday Dean .

It looks to me like the coin unit is mostly just related to number match circuit for each player and player number light on the backglass. It also controls which number ball is in play depending on how many players are in the game at the time.

You can use a green scotchbrite pad to clean the wiper fingers and the copper tracks. 

Before pulling the coin unit apart be sure the unit is in the reset position and mark a couple of the wiper fingers so you can put it back together in the right position, otherwise you would be in a world of pain  

The flippers (and probably other coils) losing power will be switch related