5x7 Automega E-3 New Antinewton Glass?

[Nokton48]

5x7 Glass Omega E3 Carrier needs new glass by Nokton48, on Flickr

This is an Automega E3 5x7 Glass Negative Carrier I just received. The top glass is missing, and the bottom has a crack in one corner. I'd like to replace them both.

I've looked at old threads, and I'm still not sure where to go. Where are the best sources for these replacement pieces? Short of buying another carrier.