Another restoration question - help me, experts!

[kai]

I might still try distilled water or a full strength vinegar with no water added to it at all to see if it is still a problem.

I'm with David. While I don't think that the water is the issue here, I strongly recommend to utilize DI water for diluting things - a gallon of pure water is cheap enough to have around at home. Spring and, even more so, well water can have really funny effects!

Regards,
Kai