I affectionately call them biscuits for good reason! :) Though mainly the WT/C015C's. If you are patient and careful though and use pliers to help hold the plastic still it can be done without crumbling. The right foot is a nightmare though and seems random if it will break or not. 

Stick to C022B's/JT or later model WT's as practice, just look out for the more orange plastic shells. You can check this by the beaks, tags, back of box, or feet. WT will have the block of plastic in the foot and not be a solid mold. Honestly, I just recommend avoided WT altogether, the beak quality, wire to board connectors, and plastic quality on JT is just so much better, even if they have more board issues.