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Replacing truss rod

I have just bought a Yamaha Studio Lord SL550s that has a broken truss rod. I have read a few tutorials on fixing the problem and it seems the only way to do it is to take the finger board off and replace the rod. The best way seems to be to heat the neck with an iron and slowly pry off the board as the glue softens. All the tutorials I found on the subject deal with necks that are removable. Mine is a set neck. Do you have any advice for this.

As an alternative I also read it's possible to dig out the wood sufficiently to re thread the rod but it seems to me the danger of that is removing too much wood that the head stock will crack or break off. What do you think?
Will appreciate any help or advice you can give me on this.
Thanks Martin

A: All I have to add is that I have run into Japanese guitars that were put together with glue that wouldn't melt. I have set bindings on fire, and still had to remove the fingerboard in pieces with a chisel. Be sure to get all pertinent measurements before you start. New slotted fingerboards are available and are amazingly cheap.

There is something to be said for replacing the broken rod with a double action rod. The original rod for that guitar will only pull the neck back. When you loosen it the string tension pulls the neck forward. This works fine on acoustic guitars, but sometimes, on electric guitars and banjos, there is not enough string tension to pull a hump out of the neck.

An iron is wider than the fingerboard. When I worked at Mossman Guitars, we used little slabs of asbestos to protect the finish while the iron was up on the fingerboard tongue. Now I use Watlow heater blankets. They are the right width, and don't threaten the finish on the top.
The stress of removal will completely wreck the fit of the joint between the fingerboard and neck. Use a sanding block to clean and refit the joint. Dry clamp it and look for gaps. Closing gaps with excessive clamping pressure in a joint that doesn't fit is especially bad on the neck. Over the years those stresses will reappear as humps, dips and twists on the playing surface.
Good luck.

Steve Mason