My guess is that one mandrel assembly is out of alignment on my one year old craftsman 20hp 42" model 917.27682.

It was scalping the lawn when going over bumps at low heights. I thought it was a bent blade but did the same
with a new blade.

I removed the deck and did some tests. One blade is at the same depth when rotated 360 (so works fine) while the
other is low on one blade tip and high on the other. It is slightly beyond the edge of the bottom of the deck,
so obviously will scalp the lawn if the deck bottoms out.

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.

I noticed that there are four bolts around the pulley/blade drive assembly and wonder if the alignment can be
corrected?

I know I can probably shim it at the blade to get it into alignment, but is there another fix?

Or is it beyond repair? I am reluctant to replace the pulley assembly in case the deck itself has an alignment
problem.

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.

Any help appreciated.

GA