Hi SueD;
Welcome to the forum. Your hose lasted much longer than mine. You can call Bradley, but if they still sell the same hose, I wouldn't get it.
I don't know where you live so I can give you some general information. If you go on the Home Depot site and search around you will find they sell a 5" flexible hose that will fit. Or you may be able to find a step down mount from 5" to 4", that way you can use a 4" hose.
If you don't use the mounting plates on each end of the hose. You will see a lip on top of the cold smoker box. A 4" hose will fit fairly well over that, and you can clamp it down with a hose clamp. The lip is fairly small so you may need a pair of wire cutters to trim the edge of the hose so that it will fit properly. The other end of the hose will fit nicely through the side of the cabinet. You do not need the mounting plates on either end.
This site
Blastgate sells 5" diameter hose, but only one PVC hose is rated FDA approved; the R-4 ECONO-PLUS. The temperature range is 20 - 160°F. The 160°F may be very close to the temperature that may be produced by the generator at that area of the box. So you may want to test the temperature at that point with the generator on, using an infrared thermometer. Another issue with that hose is that you have to purchase in 10' increments. If you go to the area of their site "Flex Hose Cut Pieces", you may find that they have remnant pieces of the hose you want that will fit your need.
Since the 5" hose may not give you a tight seal, you may also want to use a high temperature food safe silicone sealant.