RE: getting the boom tailpiece off
On some Chinook booms, you might need to open the lock collars and them "twist them off" the back of the Boom Arms.
They go right back on, and some of them (the big FE booms for sure),
and are easy to line back up with the holes.
Just open the locks with the back end still in the arms, then twist the locks a bit and pull them back onto the tailpiece tubes.
Switch your harness lines, then put the tailpiece tubes back into the arms and twist the lock back into place, lining them up so the lock pin goes through the hole in the boom arm and the hole in the tailpiece easily.
If there are bushing inside the locks, you need to line the slot in the bushings up as well.
Hope this helps,