Are there ever any special circumstances when it comes to installing screens?
Regular screens cannot be installed properly on half-round gutters or coppers (a common metal used for half-rounds). A special screen must be custom-ordered for that type of gutter. Also, though it is rare, a small percentage of normal box gutters are manufactured with an incorrect lip angle. It is the lip that the gutters snap onto. If the lip doesn’t have the proper angle, the screens won’t snap and hold correctly, leading to problems during cleaning with screens falling off. If this is the case, you should contact the company that originally installed the screens, because they may have taken advantage of you.