The yellow cutter bar is quite common on the 7ft mowers.
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As [b:654c4848f0]RayP(MI)[/b:654c4848f0] mentioned below, [i:654c4848f0]"There should be little play in the pin between the wobble drive and the knife bar header."[/i:654c4848f0]
The photo below shows this pin.
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[i:654c4848f0]"Proper hold downs and plates behind the knife bar is essential and must be properly adjusted."[/i:654c4848f0]
These knife hold-down clips may vary from mower to mower.
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Also as [b:654c4848f0]Lpmm[/b:654c4848f0] mentioned below, [i:654c4848f0]" there is a chain that goes to the drawbar it lifts the bar end just adjust to correct length."[/i:654c4848f0]
The photo below displays the pivot arm that helps raise the mower.
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The photo below displays the draw bar clevis and chain.
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Make sure that both ends of the large float spring are not broken.
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These are good mowers and <a href="http://youtu.be/_CJbfqofbUE">work very well when set up properly</a>.
Would strongly recommend that you buy an operator's manual as soon as possible if you get the mower.
Hope this helps.