Here is a couple of additional little tricks: When new balsa tri stock is added to a reinstalled or just repaired firewall, on the exposed new balsa tristock surface on the back side of the firewall that was epoxied on drip thin CA on all the exposed surface this will harden the tristock a bit soaking into the tristock and helping to prevent ripouts.

With an old airplane repairing a loose firewall as is recomended above is good but any type of glue is not going penitrate as well and the firewall itself may be a bit oil soaked. A very effective additional trick is to pin the firewall. Drill two or three 1/16 holes from outside the nose sides directly into the firewall. Tap toothpicks or 1/16 hardware store doweling into each hole and drip a drop or two of thin CA from the outside. Just sand the ends smooth and patch the film covering if that is what you have.

John