You must be logged in and verified to contact the designer.
My cap broke so I scanned it and used the data to create a new one in CAD. This cap screws onto the glass threads and uses an o-ring seal. My o-ring was brittle from age and had some glue stuck to it from a fix attempt. I replaced it with a 1-1/2" x 1-3/4"x1/8" #81 o-ring (for faucets). Your original o-ring will work if it is not damaged. This does not come with a new o-ring, If you need a replacement o-ring you should be able to find one online. I used a part number '02-1618P' from larson (purchased on Amazon). It appears the Greenlee '51316' is the same size and should also work, but I cannot confirm that.