If you’re using a newer Hamilton bill changer you should make sure that the White plug on the harness that goes down to the Hopper is disconnected, this plug will have a bright Green or Yellow tag on it. If you’re using an older Hamilton bill changer you can cut the solid white wire that goes down to the Hopper and put a male female quick disconnect on the ends. By disconnecting the solid white wire from the Hopper circuit it will disable the Hopper run switch from the bottom of the Hopper. It’s also advisable to incase the harness that goes to the Hopper in a 5/8” water hose and secure the hopper harness to the inside of the changer with rubber lined metal clamps, this will prevent the harness from being pulled out the coin cup. Something like this https://www.homedepot.com/p/Gardner...Insulated-Metal-Clamps-2-Pack-67792/100130546