Replacing springs in a Grafloc focus panel

[Jeremy]

The Graflok focus panel has 2 rather powerful springs that keep the upper and lower arms of the focus panel tight against the camera back. The arms are pressed towards the back to remove the whole focus panel so that Graflok accessories (such as roll film holders) can be attached via the slide locks.

I have 2 of these focus panels for 3 1/4 x 4 1/4, but one of them has very weak springs (they no longer have any spring). Does anyone know how to replace these springs and where to get replacements?