This is a common issue due to the SPOA pads not being welded with either a brace to the bottom pad, or welded all the way around (like with the conferr pads. Just because a weld looks nice doesn't make them strong.
You may get lucky and have reinforcement attached and not need to change out the whole axle.
Axle rap is the major cause of weak weld failure,,,
Seems I can remember bolt on SPOA pads a long time ago,but for abvious reasons they didn't go over well,,,
I can say all of this from my own trial and errors,,,
Yes, I admit I thought I was wrong once, but found out I was mistaken,,,
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