Deciphering the Blueprint

Whoever left this blueprint scribbled across graph paper clearly didn't double-check their tolerances. The heavy desk lamp was casting long, sharp shadows across the grid, so I had to haul a hefty brass paperweight out of the way just to flatten the crease. With both feet anchored on an eraser to keep from sliding, I leaned all my weight over the centerfold, tracing each flawed gear ratio with my metal index finger. A three-to-one reduction here makes zero sense without a secondary tension spring! I snatched a loose graphite pencil lead and scored a crisp correction mark right next to the faulty shaft. Much better. It's not a puzzle anymore once someone who actually knows mechanics steps in.