Hello

I am attempting to reduce speeds on some of these raymond 4700c40 4 wheel sit down counterbalance trucks, the controller strongly resembles a zapi, when i plug in my handset with the longer flat plug and fire truck up it starts into its thing and then flashes a bunch of 2 digit codes and then reads chopper not ok. I am thinking I need maybe a jumper for the handset? Thank you in advance for any help with this