Superglue will be good for cracks that don't go all the way through although epoxy would work well also.
If I was doing the repair I would use epoxy and recut the checkering at the same time, just to condense it into one step for expediency.
To measure the checkering lay the tape perpendicular to the lines, use the 16th marks.
If the marks fall directly on the lines without gaining or losing, it's 16lpi.
If, in 1/2" you gain a line, it's 18lpi