Clicking inside head during patch changes with FCB1010 MIDI pedalboard

I'm hearing a clicking inside the head when I change patches using a Behringer FCB1010 with the GM40D. I don't hear this when I use the H&K FSM-432 MIDI controller. I did have to use a 5-pin MIDI cable to connect the Behringer due to its MIDI out jack. The FSM-432 uses a 7-pin MIDI cable to the head. However, pins 6 and 7 typically run power, so I'm assuming this is used for powering the LEDs and the display for the bank number on the 432. The Behringer has it's own power cord. I've written H&K and they're saying "that sounds strange" and suggesting I contact Behringer. Anyone else run into this? Not sure if it's a relay that is switching (then why wouldn't it fire with the 432?) or something worse that shouldn't be clicking... Appreciate anyone's help! Thanks!