So I have a 2006 000-15M on the bench, and it looks like it needs a reset. There is a slight gap at the heel. I check the neck block, and there is the plate. There must be a bolt under there! I get the cap off, and... the bolt is missing. The threaded insert is there, the hole has been drilled, but no bolt. Huh.
As new as that guitar is, there's something wrong. Take it back to the dealer (or to a Martin authorized repair shop) and it should be corrected for you at no charge whatsoever.
Thanks! I actually read that article when researching this. I've found a bolt that fits, but if the owner can get it fixed for free, I will let them go that route first. If not, I will fix it for them. I may still have to remove the neck, as I checked it with the bolt in, and it's still sitting at 8/64ths on the low E. I don't think the glue joint has completely failed yet, but we will see what happens.
On the 15 series Martin uses a glued mortice and tenon where the bolt's purpose in life as originally intended is to hold things tight until the glue dries.... What instead frequently happens is that the glued joint gives way and the bolt is the only thing holding the neck on with the addition of the extension being glued as well.
Often simply removing the plate and tightening the bolt (since the glued joint has likely failed) will return the neck to an acceptable angle. When this is not the case it's neck reset time with the only difference here being that again often the glued joint has failed and steaming is not required but the extension still needs to be released with heat. When the joint has not failed David Collins has designed and crafted a threaded plug which fits the bolt treads and permits a steam probe to be inserted into the neck block which will steam the glued joint loose in short order.
Another fix for these is to add an additional threaded insert and convert the thing into a two bolt, bolt-on system.
But... if the instrument is under warranty it can be repaired for free for the client at any Martin authorized repair facility. And that would be my recommendation for this one if, again, it's under warranty. And of course any Luthier conversions to a two bolt system would void the client's warranty again if it's under warranty.
It's also possible with these to not release the extension but instead floss the heel/body joint to improve the neck angle and then reglue and install and crunch the bolt.
If the bolt is missing, which is a new one to me, and the wood plate has never been removed before this kind of sort of implies that someone forgot to install the bolt at the factory... As a politician might say, whoops, looks like someone stepped in it....;) I don't recall anything special about these bolts so after market should do fine.
I was kind of surprised to see it missing as well. I initially checked for a bolt using a magnet, and found nothing. I checked under the wood plate as a last resort, and found the empty insert. It didn't look as though it had been removed before. Maybe a Friday afternoon job at the Martin Factory...
While explaining to a customer one day that the bolts were missing from his Simon and Patrick, his hand went to his head and he said he was going to have to apologize to his kids when he got home. Apparently the bolts had loosened and fallen off inside, when he found them he thought the kids were putting stuff in his guitar.
If this is an original owner guitar then Martin will repair at no charge.
I worked on a bolted Martin mortise and tenon neck recently. There was a slight gap at the body/neck joint. I just removed and reset the neck, tightening the bolt good and tight when gluing.
Strange the bolt was missing when the cover was removed. These machine bolts are available at any hardware, they are nothing special or different than any other bolt.