I didn’t grind away the swaged end to remove it from the arm. I made a puller and simply tightened it and pulled the swaged end thru and off the arm. If you grind away the original swaged end you will be removing metal that you need to swage the new assembly back together.

I’m no expert. I’ve only done it once but it was an easy task.

Personaly i just drill them off with a drill bigger than the rivet.
Then with the new parts just practice first to be sure you started it on the right twist.
Then dont forget the seal. Then grease it up all good.
Then when in position just rest the other end of the actuator on the vice & then [lots of thens] i use a large-ish center punch [or anything to get it spreading a bit], then peen it over then flatten it down.
Probably done 100 since 1970--well lots anyway lol.
On the early AG100 farm bikes that would come in with the actuator dry & tight i used to drill a very small hole on an angle to arrive somewhere across the twist in the case.
I'd drill two holes opposing then get a needle nose grease gun trying [hoping] not to push the seal out.
Worked good at the time & luckily never broke a drill off in there.
Counted 5 thens in there!!.

Not sure why this is at the top of the list tonight but got me thinking--AT1 prefix goes up to AT3 & AT2 & AT3 have a plastic/nylon outer which makes it easy to remove the actuator with arm simply by revolving the outer bit clockwise then some force to get the seal to pull out Then now i've forgotten why were talking about this still lol. Maybe i hit a link which takes me back. I'll look later & see where i went wrong. show my post last in Feb. Don't worry, dinners up.