'''++@bperrello++'''
the springs are supposed to have give in them. Yours sound about normal. “Why do they use only a hand pinch compression clamp?” Probably easier during assembly to use teh clamps they are using. No reson why you could not repalce it. . As in why the cover broke, it’s hard to say. That would depend on where and how it is broken. Most likely some sort of fault in the making of the plastic housing. Post some pictures of where and how it is broken to give us a better idea of what you are looking at. Use this guide [guide|21499] for that. I think you’ll be okay with just replacing the pump.