On my in-ground pool, I have about a 1/4" piece broken out of the rectangular face plate on the front of my skimmer. It does NOT appear to be leaking .... though I will test it with some die tonight. It looks like about an 18" wide plate. Do I need to drain the water to replace it? How big of a job is it? Trying to decide if I should pay to have a pool company change it. I assume there is a gasket as well. Afraid I may do damage if it is stuck to the liner, etc. Looking for advice.