Air operated pins only can be retracted when the spring brakes are set(red knob pulled), and as soon as you supply air to the trailer supply, those pins are supposed to extend back through the rail, so you can't drive with the pins retracted(pulled). I had one trailer where the pins stuck in retracted position because they were misaligned, hitting the end of the pin with a heavy bar was the easiest way to get them to pop out.
Sometimes the spring brakes won't hold it to slide, and then you look for a way to block it. Sometimes applying the brakes with the trolley valve several times to adjust the slack will help but not always Heavy duty metal chocks would be nice, but sometimes you end up using somthing large and heavy on both sides to get it to slide.
I have a pin puller from a previous job, but it is made to work with pins pulled with the straight handle, and none of the trailers I pull now work with it. I could use it if I had a way to pull up with it instead of out, but I haven't had a reason to figure that out, yet.
Road debris, particularly sand, makes the slides really diffficult to move even after the pins are pulled. It may not be rust, just saying. Two pedal autoshift is also difficult to slide tandems with.
I have pulled spreads but the reefers we pull don't have them.