On Thursday, April 28, 2016 at 6:59:32 AM UTC-4, Ignoramus31353 wrote:

My question is, where can I buy him a replacement glass, any idea?
McMaster seems to have complete assemblies only?

I would try looking in the yellow pages for places that sell glass for windows. Not that I think they would have any sight glasses, but they are likely to know who does.

Dan