My '63 544 driver's side window would not go all the way down as you describe. The support bracket under the glass is C shaped. There should be a rubber C channel gasket between the bracket and glass. A tight fit between glass, gasket and bracket is required to keep the bracket from pivoting toward the inside of the door and hitting the cross link.

I rigged a "temporary" fix by jamming appropriately sized insulated electrical wire between glass and channel and tying the ends together below the bracket. Revolvo's solution is a better choice unless you enjoy taking your door apart every year or so to tighten things up.

Ron Kwas developed a mechanical brake switch for the 544.

http://www.intelab.com/swem/safety_bulletin_4.htm

Best regards,

Joe M