jcrigan, If the glove trick you tried was with those light green ones, those were nitrile. If the diaphragm rubber you bought off ebay was really neoprene, that could be the reason why they didn’t hold up. It looks like you can still get diaphragm material here:
http://www.pfs-ware.com/Parts/OllieParts.htm
I found this chart helpful.
https://www.wcrp.uk.com/technical/material-selection/which-elastomer-offers-the-best-oil-fuel-resistance/
