BELLFRUIT - Public Enemy - Pay Unit 17 Error

[TONICweb]

Hi there, hoping somebody can help, I have a Bellfruit Public Enemy Machine (non club version) using a Scorpion 4 Board. When I got the machine the MPU was faulty, so I obtained another one off ebay and popped the game card into it. Good news is it all lit up and works fine in demo mode...except for one small thing. It won't pay out. If I close all the doors I get a Pay Unit 17 Error. I have replaced the hopper with a known good one, and still not able to solve it. In test mode, it reports £1 POUND FAULT, when you try and do a coin payout test, although the hopper does move slightly. I've wiped the NVRAM and the Error logs, but to no avail. Could somebody out there with experience in these Scorp 4, Bellfruit units advise what I'm doing wrong...or not.

[psxcity]

does it have a note reader fitted??? have you stripped the hopper down to confirm no jam or debris in the hopper bed??

[TONICweb]

Hi there, no note reader fitted. I've stripped both the old and new hoppers and neither has any jams or debris. I just can't work out why it's refusing to play.