DansSIGs is correct.

The 40/357 P229 twisted-wire spring painted light blue is US-made and of substandard quality. The dark blue one is German-made. The unpainted one is identical to the dark blue one (i.e. it's also German-made, but from an era when the product catalogue was much less congested, hence no need for paint).

I've had issues with the middle strand popping out ahead of the rest of the strands on all 40/357 P229 twisted-wire springs though, German or US - doesn't seem to affect functionality.

As a side note, the 9mm P229-1 twisted-wire spring painted white is US-made and is shorter than the P228/P229 twisted-wire spring, which is German-made and never came painted. They are completely different springs entirely (unlike for example the 9mm P226 twisted-wire springs, all of which are more or less identical aside from paint and country of origin).

Mine is light blue.

MacGyver-
German un-painted twisted wire springs muzzle end were "Tinned" w/ solder to prevent the spring wire from walking out.

Easily accomplished task-
Dip the muzzle end in Acetone or MEK.
Dip the end in "Tinning Paste"
Heat w/ a BIC lighter.
Do not heat the wire to RED Hot.
Wipe off excess flux.
Oil for storage.

I have fusion TIG welded numerous twisted wire springs to prevent wire(s) walking out.

Sigfreund's replacement spring arrived yesterday, and in fact he sent two! One has light blue paint on the tail, the other is one of those he mentioned, early Sig production without paint.

I installed one last night, and it was a bit of a struggle, tight around the guide rod and getting it into the slide and locked to the barrel reminded me of taking a cat to the Vet!

I really needed this spring, more than I realized!

I'll try to get to the local range this weekend, along with some .357 Sig practice ammo I got last month.

Thanks to all who helped, especially sigfreund, of course!