Just an old man throwing this in for thought....
Brewing since 1984.
Several have mentioned simply drawing around the piece of stopper that has broken off and now is now in the AAS vial....
This is different from mfg to mfg but, is it the outsides of the stoppers that are sterilized after they are molded, or, are the stopper fillers and binding agents sterilized as well?
Try this...
Tear or cut a stopper in half and compare the texture from inside to outside.
But before you tear or cut the stopper, submerge it in a glass bowl, filled with safflower, cottonseed, grape seed oil. Or any common transfer oil.
While tearing or cutting the stopper, use a magnifying glass for close observation. Do you see one very, very small bubble escape in the process? Most of the time it will be several. Watch closely.
Using distilled water will do but watch quickly. In tap, spring, or purified water, the bubbles get away too quickly to see in most cases.
Question:
Is the air inside the bubble that was in the stopper sterile or does it carry contaminants from the air where the stopper was molded and you are releasing foreign air into your gear?
Same with plunging the pin and bubbles seep into the vial. Slow and gently is best. At least that's what she said.
Most stoppers are molded with high heat but is the heat hot enough to kill contaminants in the air or just hot enough to bind the stopper?
Health and safety is #1. I've learned the hard way and pay for it every day now.
Good luck brothers. Take care of yourselves now so you are able to in the future also.