George Abbot wrote:
....
old craftsman 20hp 42" model 917.27682.
....
... other is low on one blade tip and high on the other. ...

If the blade is removed and replaced about 180, the low/high reverses.

If the blades are swapped, the low/high is still about the same on the
same mandrel.
....

The last two statements are contradictory -- if the high/low position
interchanges when the blade is rotated 180 degrees on the spindle, that
would indicate a bent blade as any tilt or bend in the shaft would be
the same and the location of the low spot moved w/ the blade.

OTOH, if swapping blades doesn't change the symptoms, the blade isn't
bent (or the even more unlikely that they're both bent exactly the same
way).

Unfortunately, the machine did not come with a IPB of the mower deck,
only the tractor, so I cannot figure out just what is involved in the
pulley/blade drive assembly.

There would likely be a parts diagram on the Sears web site for the deck
as well I would think...

First check to see if the shaft of the offending spindle is bent. If
you have a dial indicator, that's the most direct way, but you can
improvise w/ any tool you can position at the side of the shaft where
the blade mounts and rotate it slowly to see if the distance between the
shaft and the tool point changes. If it does, that indicates the shaft
is bent which would provide the symptoms (other than the dichotomy noted
above). It would have to be replace as it will be treated.

It is also possible the deck where the mandrel mounts got bent if hit
something or that there's a combination of both bent spindle and deck.
It would seem unlikely the mounting itself would be able to cause a
camber as the castings are likely just bolted directly to the deck so a
movement there would simply be lateral, not angular--but, that would
need a picture to see clearly.

I'm guess the most likely is the shaft is bent...

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