Another Helicomatic problem not mentioned is how loosely (mine at least) they sit on the splines. I have two that wobble excessively and have way too much play after they've been attached to the hub.

On a side note I have two Trek 610's, both produced on the same day in July of 84'. While one has the Helicomatic, the other has an original traditional hub with the red band, maybe a Normandy Luxe? Even has a metal pie plate.