So the issue is the gap (0.5mm) between the stanchions and the caps? Would an o-ring solve the problem Caspar? Need a pic to better understand I guess.
I see. So that's a tough call since a potential and permanent solution may prohibit easy access to the internals long term. Do you plan on riding/using the fork? I assume so.
If you use a proper industrial strength epoxy adhesive the gap between the two parts makes sense. I would suggest "Loctite Hysol 9430" (has one the highest shear and peel strength off all the commercially available adhesives out there). This adhesive requires a ca. 0.25 mm radial gap between the two materials in order to form a proper bond-line. (look up bond line control) Sometimes you can mix tiny glass beads into the adhesive to insure an even bond line. That being said bonding into a threaded part seems... well... wonky. don't get it why they would have threaded the surface if those parts are supposed to be bonded but I guess it should still work. This particular adhesive is very viscous so it will fill up the threads. The down side: it's expensive (mainly because it doesn't come in small quantities).