|Reverse stress stake out|
Now, after I remove the impellor and give the blades a good inspection for deterioration, I stake it out on a piece of wood with nails and distort the offending blades back in the opposite direction. I leave this for a few weeks/months until the blades look close to "normal" again.
If the impeller came from the raw water pump about to be used. I just put in a new one to get the boat going, and place the "recovered one" into spares as it becomes "UN-distorted:"
This trick should save me some money. I hope it does for you too!