I had what sounds like the same problem: when I rolled up and down the passenger window, the crank arm felt loose and unsecure.
I recently replaced my door panels, which exposes the innards of the door and the entire rolling up mechanism.
The crank assembly is supported by 3 small bolts. On mine, one was gone, and the other two where loose. These bolts are short
as to not interfere with the window as it goes up and down. I replaced the missing one and tightened the other two and it now
cranks perfectly.
Hope this helps.