Mower deck Lower Center Blade Cut on JD 657 Stander

My JD 657 was starting to cut lower at the center blade compared to the two outside blades, so I changed them all to stock blades thinking one might be overly warn or bent slightly. Now the uneven cut is even more noticeable. When examined, they appear even and level across all three over a hard surface. The lower cut is constant, meaning not wavy. The spindle doesn't appear to have any play.

I tried to lower the height setting, from the second highest to the third highest, but it started basically scalping at the dirt.

Any thoughts to help would be greatly appreciated at this point.

Jimmy