Did he say that Elmer's was okay? I would kind of be surprised if somehow Elmer's didn't cause the same issues as 505, but I don't know.
I have an old Singer Genie 353 & just about anything will gum up the needle and bobbin (even Wonder Under, to a degree, and Roxanne's Glue Baste-It). I use the off-set safety pins & that works for me. Really, the straight pins with Pin Moors work better, but those things are so expensive that I stick with the special safety pins.
Nancy Zieman suggests using little 1/2" bits of Steam-a-Seam 2. You just stick it on a bunch of places & tack in place with the iron. I've used it on sewing projects before & it's super easy to use. If nothing else works, maybe you could try that. It's the second segment of this 6 minute video:
https://www.youtube.com/watch?v=MSeWBOnbC90