Saw this post and thought - why not ask the experienced pragmatic
folk?

Sadly these calipers emerged from an overnight dunking with the spring
broken. It looks like it's probably been cracked for some time.

...
spring steel does not respond well to acid derusting.

Working with weldable structural steels, I was once totally
disbelieving of how susceptible bolts and some hardened steels are to
hydrogen and the effect of acid pickling.

Millions of times more susceptible...

How many of you have been involved in sorting out delayed
cold-cracking breaking of bolts and studs?

Rich