I have a water bubble behind the liner along the water line and I want to pop off a couple feet of liner to test the water and see if it is caused by a leak or groundwater. However, I am having a hard time getting the liner out of track without damaging the liner. Any suggestions? I read somewhere to use a butter knife wedged in between the liner and track to pry it out, but I am not having any luck. My liner is only 1-1/2 years old, so it is still pliable and I can get some slack in it. Maybe my technique is just not right. Thanks for any help.