IH Model 100 Sickle mower

Check the wobble box for any play. With the pin in and attached to the knife, turn the drive pulley to see how much free play is on arm that drives the knife. A little here is ok. Remove the drive belt and try to wiggle the large pulley. There should be no play here. Remove the pin that drives the knife and check the arm for any vertical play. Very slight play here is allowable. If there is any major amounts of play in any of these areas, then plan on rebuilding the wobble box.

You did not say how long the bar is. With hard use the 9 foot bars have a habit of breaking off right at the point where it meets the wobble box. You may need to remove the grass shoe to inspect this area, but if you do BE CAREFUL. The bar will no longer attached to the wobble box at this point. It could fall and injure someone.

Check the breakaway casting. Look around the support for the vertical pin that the lift linkage pivots around. This casting can crack after too many hard acres.

Good luck

John