I bought a 6600 a while back the header sits lower on the left side. when raising the right cylinder tops out an inch before the left one, when both are at top it is level . when lowering the left cylinder goes down an inch before the right one ever moves, the feeder house has no apparent buckles or creases in it, that would normally show with a twisted feeder house. everything seems to be in real good shape with normal wear on pins etc. the fella i bought it from said it was that way when he bought it 10 yrs ago they ran a weight on the high side.... any ideas besides a twisted feeder house?