Back in the 80's up at Harry P. Cues we use to play on Gold Crown W's and do a lot of gambling. Sometimes because of the amount of money...and "rules of the rail birds" the players would have to post the money up on top of the pool light. I remember a game once that involved $16,000.00 in race to 125 playing 14.1 straight pool. Harry was ahead 121 to 52 when he missed. I ran out from there to win...LOL..oh, that's another story...LMAO. Anyway the point of this story is that because everyone was always climbing on top of the table to recover the money off the pool light I could never keep the seams together on that one particular pool table. Bound and determined to fix the table once and for all, as I took the table apart again to fix the seams...once again, I got a wonderful idea...why don't I just super glue the slates together and then I'll never have to worry about having to fix them ever again...so I went out, got me some super glue...and glued the slates aaaaaaall the way across the seams. Never had to worry about them coming apart again after that. So, I learned something good from that bad experience of having to fix another broken seam, I never had to fix them anywhere else...just there, and just on that one particular pool table. I also learned when Harry P. Cues closed down years later how much super glue NOT to use....LMFAO!
So, in answer to your question, super glue the slates in 3 places. 1" from the outside edge of the slates for about 3 to 4" inward. Then in the middle of the slates about the same 3 to 4". As your in the process of leveling the slates, place 1 to 2 business cards between the slates where you're going to be placing the super glue. Go ahead and finish leveling the slates. Then before you finish the seams cut the business cards off flush with the surface of the slates. Place the super glue on top of the business cards, gluing the slates and business cards all at once. The business cards act like a dowel for the glue. And they also make it a lot easier to take the slates apart at a later date.
Glen