The pin will only go through completely if everything is in alignment. If you can get it to go all the way thru- you are golden. If you think you have to take it apart- yes you have to unsolder a terminal. The difficulty comes in re-soldering which takes some skill. The solenoid wire needs to be straightened and solder removed so that it now can be wrapped around the terminal and re-soldered. If this is your first time, I wouldn't recommend it. Or maybe a friend could help?
