Help with using a "Image Magnifier Glass" on photos on webpage

(Apologies if this is wrong forum!) I’m trying to help my grandpa add a magnifying glass for on his weebly webpage on postage stamps. We tried the two “apps” that weebly offered, but they are very problematic.

So I tried the one at
https://www.w3schools.com/howto/howto_js_image_magnifier_glass.asp
I know nothing about webpages, but I tried replacing their image URL with our own, and pasted the resulting block of code into an “embed code” box on weebly – and it worked great!..

Except that we can only do one image per page. If I do this on more than one image, only the top one works.

Is there a way for a novice to adjust that code so the magnifier would work on multiple images on the same webpage?

(I’m assuming there’s no way to add a magnifer globally, to every photo – but one at a time would be enough.)

Thanks!

PS - here’s an implementation of it that only allows one use (on on image) per page: