The only danger of parts falling out are when you take apart the switch itself. There is a steel ball, a spring and a latch mechanism that are notorious for launching themselves once the switch is opened up. I highly advise you get a white or light colored bed sheet and spread it on the garage floor before attempting this. Don't ask me how I know this.....
Rebuilding the switches can be done if you are careful, have decent finger dexterity, take your time and are patient. If you start getting frustrated, put it down and take a break.
Also suggest taking pictures of the inside of the clusters for future reference to be able to see exactly how they go back together. Those clusters are packed and must be reassembled the same way for them to fit back together properly.
Good luck.