Danl, you can remove the top rail to better expose the track - a lot of times you absolutely HAVE to to gain the access you need. If you are doing multiple 'liner tucks', replace as much as you can before proceeding to the next one - some of them may require having 2 off at a time, because it falls at an upright (I'm assuming that we are talking about an AG pool)

As a tip on reinstalling the top rail, don't fully tighten any of the screws down all the way until all 4 screws are started and the rail sits in it's proper position

Thank you Janet !