Slipping wiper arm connection

We have a 1999 Saturn SW1 with 56k miles.
Windshield wiper noise has been a chronic problem. After many attempted fixes, I recently installed a set of Bosch ICON blades, which are solid rubber (no multiple metal pivots). In our first rain since, they worked great until the passenger side wiper arm began slipping. I assume that it connects to the rotating shaft in some way that allows some give if on turns on the wipers when the blades are frozen to the windshild. But I need more torque and cannot see how to tighten the assembly. When stopped, it is easy to move the passenger blade back to it's proper place, but in the heavy rain at highway speeds it would get hung up and driver blade ran into it. Ideas? Thanks, Rob