From Dean Morrissey's 1997 book The Great Kettles: A Tale of Time, page 33.

Put your hand on the retro lever and never take it off, no matter what. When the elevator stops, you'll have about five seconds to see if you're in the right place. If you land anywhere else - and I mean anywhere else - pull the lever. You'll be returned to the clock tower and we can make the necessary adjustments. - Dean Morrissey