I took the pulley to the bearing shop today. Find out it is an oddball metric size not quite 15mm and too small for 14mm. It appears to be about 14.75mm but with a dial indicator .582 was measured in 3 locations. .0581 is pretty close to 14.75 in conversion, so will try locking the dial caliper there and slipping it over the shaft.
Called Jet while at the bearing place, they confirmed it was metric but would not disclose the size of the shaft as they still sell the pulley as a replacement part.
I've asked the bearing guys to see about opening a 1/2" machined pulley and cutting in the 5mm keyway. Won't hear on that until at least Monday. It appears no one sells a machined pulley for the jet contractor saws.
Alan
keywords for search: jet table saw TS pulley arbor metric cast machined