Stax tonearm idiosyncracy

I recently acquired a 9-inch Stax tonearm as part of a turntable deal. It's got an S-shaped arm tube that is joined to the pivot via a connection much like that which is used to attach the headshell to the other end of the tube. But at the joint near the pivot, the arm tube is "floppy". It does not make a rigid connection to the pivot point. The seller tells me this is normal. I find it hard to believe, but I am looking for comments from anyone who has ever used one of these. Thanks.