Finnbear
ArboristSite Operative
You can't use the later two forms of vents on the older 026. What you can do though is install the flapper valve (trickier than it looks..) part number 1110 353 1600.. About $4.00.
Does this part # look like a little orange umbrella? My receipt doesn't show any part numbers and they didn't even look at the number I gave them-the guy just went over to a parts bin and grabbed this little orange thing and said "this will fix it".