Usually the DIP switches control the coin switches. It does have some strange behaviour if it is only adding credits on the RHS once a game starts.
The techy had the same thing happen with it not turning on but then it was okay. He thinks one of the 'switching spider chips' might be playing up. Hopefully it will hang in there a bit longer so I don't have to buy a replacement board. I'm replacing the diodes on the cabinet base and I'm in the process of repinning so I'll let you know how it progresses. 
If it is a spider chip, you will have to find a replacement board (easy). The 5 second delay as the game boots is normal. The GI relay switches on and off and then the displays light up.
The board's got a bit of life left in it yet. Once it does start up, I leave it on and you can play it all day without a problem! Occasionally, the 1000 will chime, but usually not. I changed those diodes in the cabinet but that wasn't it...must be the connectors like you suggested. Thought it might be the coin door as you can add credits with the left coin mech but not the right. Then when it does start up the right coin mech will add credits??
