I have a new RDM mast extension from Chinook. I can't for the life of me get the collar pins to seat into the aluminum. I've had a few Chinook extensions over the years and have never had this problem. In about 40 minutes of wrestling with it, I've managed to get it seated into the holes three times. Each time it worked it just sort of snapped into place - I don't know what I did differently. Once in the holes it's easy to snap out by pushing/twisting it with my thumb. This collar has 4 pins whereas my older SDM extension has only 2 pins.
Any clues on how to do this? It can't be this hard...