Pretty sure they should be soldered on, could be wrong.

I think crimping them would damage the contact surface. I'd solder them.

I've always heard pliers and/or solder...Pliers aren't going to damage the contacts...If you're worried, insert a business card in between the Pliers and contact when you spread the crimps.

Lay the surface of the contact on a piece of wood, slip your leaf over the peg on the back of the contact. Use a punch with a nice wide 45* angle to the tip, give the "nub" on the back of the contact a solid wack with a hammer, you dont have to kill it but give it a solid one. One more wack to the contact "nub" with just the hammer after that.

Im talking about a round punch that jets out at about a 45* angle from the tip, not a chisle.

I prefer to solder the contacts as it assures good continuity between the blade and contact.

For hardened or spring steel use a propane torch, black flux and I use silver solder, but regular solder will also work.

Pinstyle's approach would also work. Either way should give a good connection, just a matter of preference.

I solder them in - electric gun

Bringing this thread back to life.
The idea of fixing a few switches on my game for a couple dollars sounds great but the dollar amount climbs by buying a press.
Did the channel locks pliers work for this?

I’ve used a similar technique as described in an earlier post (quoted below). The back of the contact has a flange (“nub”) that can be bent down with a simple nail punch that shouldn’t cost more than a few bucks.

You can use pliers, just put some padding (rag) on the contact side to protect it (essential if you are doing gold flashed ones). It also works to solder them in, as does the nail punch. I vary which way I'm doing it based on how many I'm doing and where (in the machine, on the bench, etc.)

As for the way earlier post about hardened switch blades not being solderable, that's not true... I had to solder an extension onto a pinbot flipper EOS during a party, and all I did was shine up with a bit of sandpaper each side (there was about 3/8" overlap between the snapped blade and the extension) - iron soldered it fine, it survived the party and 7 more years (I forgot I had did it and when I was selling the machine the buyer was like, WTF is this???)