The first fretted CBG I pressed the frets into the cuts and they mostly held just fine. Over time two fell out and once they did they continue fall out despite firm re-hammering of them.
So I tried just a dot of CA glue (thick) and it oozed on to the fret board which was unsightly.
Is there a specific glue and/or gluing technique I need to use/follow?
Most gluing of frets I've seen, including myself, merely use a dab of "super glue" the clear very thin stuff you can buy anywhere from dollar stores to Walmart, not so much in the slot, but on the ends. You tap in your frets, then turn the neck sideways and drip a drop at both ends of the fret, it usually seeps into the slot beneath the fret making contact with the fret and soaking into the wood due to it's thin viscosity.
Soft wood finger/fret boards tend to not be as secure holding the frets as much as a hardwood does, and make sure your making a thin as possible kerf slot for your fret, experiment on a piece of scrap, till you get the slot thickness to feel just right before cutting all of them on your finished gee-tar.
To resolve the issue at hand, you can still try this method, or you may have to remove the offending frets as they come loose, make 50/50 mixture of hardwood sawdust and wood glue, press it into the slot, and immediately tamp the fret back in, excess will squeeze out the sides, wipe, wait to dry, add the superglue to the ends for extra security.
Do not use the gorilla glue products as as these glues dry, they expand, making a mess, possibly even pushing the fret back out.
The very worse case scenario, slots are too loose and you have to let the 50/50 sawdust glue mixture dry before you insert frets, filling in the old slot, and re-cut the slots thinner.
Phil, I have had the same CA experience in the past....more glue outside than in. My solution, after diggin' around in CBN, Stew Mac, etc, was to purchase some "water thin" CA. It's available from many sources. I bought some STARBOND brand EM-O2 in a small kit that included several small "hummingbird beak" nozzles which allow great control over the distribution of the CA. I recall it was @ $10 from Amazon. It is Very Thin! Good CA bond, easy to control and use. Don't squeeze the bottle, just let it flow. Good luck
I have also read many tales of fret gluing on this site, but I have never needed to use glue. I just use a fret saw (stewmac) and hammer them or press them in place. Ive never had them fall out as they usually fit pretty snug in place. But if I did, perhaps I would do it after finishing the neck with tung oil, which may help removing the excess glue.