Just take the bolt off the trunion, get yourself a wide flat screwdriver, insert it into the incision on the trunion, and gently tap it with a hammer to widen it.

You do not have to sand the strut.

Try it, it works every time. If you can put it in using above prescribed method, you can also take it off when need using the same methodology. Just make sure you do not over tighten the bolt on the trunion and put indentation or deform the strut.