I finally got my skimmer delivered. here is a picture of the old one. And wouldn't you know the plumbing is the wrong size. I have 2" pipes and after I took it out completely I found for some reason they down sized at the skimmer to 1-1/2" . So i'm either going to have to reduce like the original manufacturer did (no idea why they did that, its the only thing on the line) or re plumb that area with 2" pipe. I haven't dug any further but I'm guessing I will find a coupling with a 2" to 1-1/2" reducer on it.
from what I saw on the first picture above I was planing on clearing away the grout and then using a silicone adhesive to stick the new skimmer in the opening after it was plumbed in and then grout in place. But one side is not smooth at all. this was where my leak was or at least most of it. all the way to the left there is something that looks like a crack but its a saw cut.
So now i'm thinking of one of 2 things. rebuilding the area completely or smoothing out the rough area with some fortified cement product and continuing from there as planned.