Rather than try to find a hypodermic needle, I have successfully
used a mechanical pencil with no lead inserted (or just retract the
lead a few millimeters).  No modifications needed.

These also come in various bore diameters, 0.7 mm and 0.5 mm being
the most common.  Use the smallest bore that will fit over the pin.
I had very good results on a Mermod Freres box with one.

Mike Knudsen