Today I discovered that my Polaris pool cleaner lost a wheel. The wheel, along with a screw and small metal plate, were on the bottom of the deep end. While trying to scoop these small pieces off the bottom with a net, I thought to myself "I hope this won't tear or scratch the liner!" How durable are liners and what does it take to tear them? Mine is about 10 years old and seems to be in great shape except for fading.