By tight I meant they were fitting tight enough inside, with not much slack. Once I put a thin layer of the black sealer on them, it actually took considerable force to slide them in place. Thanks for advise, I'll do the straight edge measurement and look inside with a snake camera to check if they bonded to both sides. I'm thinking, since the ribs are only about 1" in height by 5" in length, even if they were cut to 97% of the original size, a 1/16" layer of sealer should compensate for that. Perhaps, I'm rationalizing.