Neck crack repair advice needed.

I'll guess it was turned into something, (mic, pole, wall) banged and the "cracks" are finish stress-cracks. You can see an indented dot on the darker stripe right at the source of the 'crack'. Wood is elastic- an old thick clear coat isn't.

 

I agree, it looks like it may just be cracks in the finish. If it bothers you, you could remove the finish from the neck and refinish it. Removing the finish would also be a surefire way to tell if the crack is actually in the wood! If it turned out there were cracks in the wood, you could easily wick thin CA into it at that point. Then, refinish with something easy like wipe on oil based satin poly or tru oil, both of which are pretty foolproof and give that smooth fast natural-feeling finish most people seem to like.

If it doesn't bother you, you may want to just keep an eye on it, and if the cracks seem to spread over time, drop fill them with CA to keep it stable.

 

I recently discovered a product called “Birchwood and Casey gun stock sealer and filler“, I bought a neck on here that was a bit beat up but otherwise fine, I sanded it till smooth with 220/320 then put 3 coats of the product on and sanded with 320 then a green pad and am super happy with the neck, I would recommend this process highly.
https://www.amazon.com/Casey-Stock-Clear-Sealer-Filler/dp/B001MQNJ40

 

CA - CyanoAcrylate a.k.a. super glue.

 

If you enlarge that picture far enough (I can make the ding @JIO mentioned 35 mm wide [about 1.5 inches]), it becomes obvious those are not finish cracks. The darker wood is split and the split even jumps the grain making two distinct cracks, and they have debris in them. The finish does have some cracks on the outside laminate. The way the finish cracks are running parallel to one another makes me think this is from the wood being stressed.

 

Looks like a stress crack from here, especially how it arcs upwards along the headstock heel.

I'd not put any heavier or higher tension strings on it.

What happens when you take the strings off? Does it creak or twist?

 

That looks very stable to me. I would sand it nice and smooth and add another coat or two of poly.

 

Don't wick any glue into the cracks, in case a pro repair is required in the future.

If you have balls of steel, take a brand new, single edge razor blade; and using both hands, gently scrape the high point of the crack's finish.

The razor should be at a 90* angle to the surface, not 45*. <- Read this again.

Because the blade is brand new, it will just kiss the sharp edge of the crack.

This will keep you from feeling it always with your thumb.

 

I know just enough about finishing wood to give bad advice. That said, I'd try to clean out the cracks with either the tip of a razor or some canned air and wick in some thin CA bringing it proud of the surface. Next, I'd sand/polish it smooth and call it a day. Do you suppose that will work?

 

@sissy kathy I'd say that is pretty good advice. Drop filling with CA is a pretty standard method of fixing cracks or chips in instrument finishes. Stewmac has a video on the process, you can ignore the part about adding the colored stain first but the razor blade trick is a good step to take since it results in a nice level repair that doesn't need aggressive sanding/buffing.