You can usually find it on Ebay like this one Perfecto Aquarium Glass Canopy Replacement Hinge 1/8" | eBay but make sure you get the correct one for the glass your using. Either 1/8 or 3/16.


Also many place to order online but usually they have a minimum order cost or a huge shipping charge.

I tried to use the hinge from old canopy tops but the glass is usually suck in so well that you either ruin the hinge or get cut trying to break it free.