My Silca Presta pump went in the dumpster years ago but I kept the head (photo) and have been using it with a different pump ever since. The rubber washer (see photos) needs to be replaced but what I have looks different from what is offered as a replacement these days. See link:

Silca 24 1 Large Rubber Washer for Presta Valve Head | eBay

I notice they have 24.0 and 24.1 models. Dimensions seem right: 20 mm x 4 mm thick.



My assumption is the current version is compatible.

And BTW $5 or more seems a little high for a washer