There is a safety stop on the baler that should prevent the needles from breakage. On the left side of bale case near the needle frame is a boomerang shaped part connected to a long rod. As soon as the needles start to move, the needle frame moves away from the boomerang and allows the plungerhead stop to move into position to stop the plungerhead arm. When the needles move back into "home" position, the plungerhaed stop is moved back out of the way. There is a spring under the top front cover that pulls the stop out into the stop position. If the spring breaks, the stop won't work and needles are unprotected. Or if spring is ok, then the linkage could be forzen so the spring is not strong enough to move the stop. So, timing should not cause needles to break if safety stop is working ok. You should only shear a pin in flywheel. The biggest reason for broken needles is a broken stop spring alng with a loose or worn out needle/knotter brake. If the brake is loose, it will allow needles to "drift" down into the chamber when they are not supposed to. So tighten the brake and check plungerhead safety stop spring.
