No, but it screws into the body on most automotive carburetors (which are more complex and expensive devices). My point was, you may be able to pinpoint the leakage path by using the same process the old carb guy used. Once you prove that the needle and seat won't hold vacuum, you can try temporarily sealing off various possible leak-points. The only leakage paths that occur to me are between the needle and seat, or around the outside of the seat. Your seat is pressed in, not screwed in. If you can temporarily seal one of the two leakage paths and do a vacuum test, if it still leaks, it must be the other path. Then you can verify this by opening the first path and sealing the second.
