www.KitGuitarsForum.com

1969 Yamaha f 140 needs a neck reset. this would be a labor of love. Would this be a mystery glue Yamaha or is it early enough to be something else.
Any helpful advise would be great.

it could be
here is the best advice I can give.
If after 5 min you don't see anything happening you may want to cut the fret board off about 2 to 4 frets up the neck. Remove that and you can now really see the neck joint and attack that with better visibility.

I do find that you may also do this first

pull the body fret and one below say 14 and 15
drill 2 holes on each slot the body joint you should feel a pocket so drill one at a slight slant to the sound hole if that don't work then angle the other straight down or slanted the other direction. I would think the opening would be more at the sound hole side.
work you steam after the fretboard extension is loosened. This may five you a glue to the glue used.
then rotate the 15th fret holes if you don't see anything happening in 3 min you may want to use the other 2 holes. If the guitar was finished after assembly this will help get the heel off with less damage.

don't rush and take some pics to share for others
thanks

Thanks John i'll give it a shot.

I have a treasure cooker for making steam. What do you use for a steam needle?

I use the one from Stew mac