Having grown up in Seattle I know that structural corrosion is not a big issue in the Pacific Northwest, so that leaves the cause as just plain old fatigue or overloading in service due to something like fast driving on poor roads - something on the order of what a pro rally car sees.

I recall one other report on this forum of spring perch failure on a 201 or 124, but I think that car may have had a lot of other structural corrosion.

Let us know the repair estimate and your course of action. I'll be giving my spring perches a thorough inspection at the next maintenance interval!

Duke