Are they the older style or the new style, cause with the newer style you need to replace the entire baseplate. For the older style watch this (obviously skipping the bending steps unless needed):
Well, you can change the new ones the same way, but you'd have to get the brake from somewhere, Rossi just sells the entire baseplate to you to make it easier.
When taking apart FKS, you need to be %100 In , or %100 out. Its a fucking bitch to say the least, and it will probably leave you frusterated as hell the first few times. Personally i like taking things apart, and after hours of rage mixxed with old broken fks parts, i can take apart/ put them back together pretty quickly.
i got to puting the spring in and gave up its such a bitch i left the beaks off and just in the box ill just haave the shop do it when they mount my skis.
You need a tiny screw driver, with a small handle on it, and a rubber mallet. like shown in the video. but the handle against the spring, and use the mallet to drive the svrewdriver into the brake. just work on it, and you'll learn your own way of doing it.