Thanks for the tip. I've been sticking all manner of things in the hole and I've found that one of those little red plastic extenders for canned air fits perfectly but I can't properly eyeball 2.1/2.5mm when I place it against a mm ruler ;(


My calipers are saying 2.8mm OD for the red tube on a WD40, but then maybe mines thicker than yours...
Much appreciated yefi! I left before I saw your reply and took the tube with me. Turns out that 2.5mm was my best bet.