On Thu, 28 Apr 2016 05:59:30 -0500, Ignoramus31353
wrote:

I sold a customer this hoist, and, unfortunately, upon delivery the
sight glass was broken.

Here are some pictures:

http://igor.chudov.com/tmp/Sight-Glass/

He says that it is a round glass with a little groove for a o-ring.

My question is, where can I buy him a replacement glass, any idea?
McMaster seems to have complete assemblies only?
Try the manufacturer of the hoist, or better yet, go to the class
source,Swift Glass, Corning New york - contact 131 W. 22nd Street,
Elmira, NY 14903 • Phone 607.733.7166 You want a borosilicate
sight glass - give them the diameter and thickness and I'm sure they
can fix you up. They carry Corning, Schott, Pilkington, Maxos, etc.