I have a oneway vacuum adapter and was curious whether anyone knows if it can be used on 1840 Jet. My new Jet has an outboard headstock fine thread spindle that measures .745 inches. The oneway vacuum adapter has a removable insert with 1-1/4 x 8 threads. I got the oneway adapter in an auction and it was used on an older grizzly. The insert is what I need and am having difficulty locating.