K8b restoration

On Friday, February 22, 2019 at 10:00:06 AM UTC-7, Eric Munk wrote:
I think you will find that all wooden Schleicher gliders have been finished
from the factory with fabric up to 50 mm forward of the rear face of the
main spar, and with paint on the D-box. Sometimes the D-box has been
reworked (especially on Ka6s) with a thin layer of filler to reduce drag.
In fact, reducing drag by creating a smooth painted surface opposed to a
more rough fabric'ed D-nose is probably the main reason it was finished
this way. Fabric width was no problem.

What glue is recommended for fixing broken glue joints? I understand that the original glue was not the best--very brittle.