Before filing down the base of the tube, which may have been required in Rwd's case, check out the collet ring at the base of the vacumm post (not the tube). This ring has an allen set screw that you use to adjust the height of the vacuum wand when it is "sucked down" on the record surface. If the ring is "canted" it will not allow the wand to make even contact. This worked for me.
My 16.5 is far and away the best analog accessory I've ever bought. Worth every scheckel. Look for one in good condition used and you can save but, in my opinion, they are worth the retail price. Not many things you can say THAT about.