Ensure the tractor & trailer are straight
Ensure trailer brakes are released (Red Knob pulled out in the truck)
Pull the tandem slide knob (or sometimes required to push it)
Drivers will hear the air release from the tandem pins, pins may not retract immediately and that is okay, it just means that the weight of the trailer is pushing against the pins.
Get back in the truck, with window open to hear the pins, release tractor brakes, keep truck brakes set, and rock the trailer a small amount, forward and backwards to release the pins.
Confirm the tandems are where you want them
Push or pull the tandem slide knob back in, drivers will hear air refill the system.
Rock the trailer forward or backwards with the trailer brakes still set to lock in the pins.
Tip: Put truck into 1st gear, and lock the power divider before moving to ensure maximum power