How to trouble shoot a Heng Long TK-7.0 main board?

[keilau]

I installed the metal barrel recoil BB unit on the Sherman with TK-7.0 that I acquired last November. Everything work as they should EXCEPT the barrel recoil!!! The recoil BB unit was tested on another tank. I push the barrel in to verify there is no obstruction of movement. Was the trigger signal at CN6 turned off? Is it possible? Do I get a faulty TK-7.0 main board? Any suggestion is appreciated.

[SoCalBobS]

The manual lists a command input for either the Airsoft sequence - windup, trigger, fire - or just fire. G & K I believe, toggles the option back and forth.

[keilau]

The manual lists a command input for either the Airsoft sequence - windup, trigger, fire - or just fire. G & K I believe, toggles the option back and forth.

@SoCalBobS, thank you for your inspiration. The "G + B" function swith works for me. Now, the Sherman is barrel recoiling as it should.

Case closed.