3 phase motor

[Jraef]

No load not coupled to anything motor only

Then it can only be the tweaked frame issue in my opinion. Rolled steel motor frames are notorious for this because as mentioned, cast aluminum frames will often break rather than twist and cast iron frames are so rigid that they can warp the base or pull anchors out of concrete if not flat, so you know right away when you made the mistake.

When a motor is removed, it's common practice to use a scratch awl or even a sharpie pen to mark the shims, the frame and the base so that the shims go back into the same place in the same way to correct for flatness issues. I've seen where unskilled people remove motors and don't know to do that, they think the shims are just there to act like washers so they put them back in randomly or not at all. I'm guessing that's what has happened here.

 

[GoldDigger]

So it could be as simple as the other motors having sufficiently flat bases while the needed shims were lost from the problem one.
If there are shims on the problem machine, they may indeed simply by arranged incorrectly.

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[kwired]

Then it can only be the tweaked frame issue in my opinion. Rolled steel motor frames are notorious for this because as mentioned, cast aluminum frames will often break rather than twist and cast iron frames are so rigid that they can warp the base or pull anchors out of concrete if not flat, so you know right away when you made the mistake.

When a motor is removed, it's common practice to use a scratch awl or even a sharpie pen to mark the shims, the frame and the base so that the shims go back into the same place in the same way to correct for flatness issues. I've seen where unskilled people remove motors and don't know to do that, they think the shims are just there to act like washers so they put them back in randomly or not at all. I'm guessing that's what has happened here.

OP has a 125HP motor, do they make them with rolled steel frames? Can't recall seeing any over about 20 -25 HP.