Are my wipers working properly???!!

I bought a used 1991 500 SL. I read in my owner's manual that when you have the windshield wipers on and you slow down or put on the brake, the wiper drops down to the next lower level.

What MY car does is if it's on the medium speed and drops down to intermittent, the wiper stops in the middle of the windshield, and when the intermittent runs it doesn't make a complete swipe from one side to the other. Is this right??

When in intermittent wiper setting should the wiper go completely from left to right and not stop somewhere in the middle?

If not, is there a setting I could adjust??

THANKS

it shouldnt stop in them middle ...turn off wipers , now is if the wiper linkage is bad by pulling out on ,,wiper arm ..it has the extended wipe linkage some times the plastic gears break .