Hi Everyone,
I want to update what happened with my trying to get service for my Concert Keyboard Amp. As I mentioned, when I first called, I was told that I would need either the original sales receipt or the warranty card as proof of ownership. I looked for them in vain. I then looked at my amp and noticed that on the sliver sticker (the "Personal Lifetime Warranty Validation Sticker", which came back with the warranty card), there was not only the reg#, but my name pre-printed from the company (there is also an area on the bottom where you sign your name, which embosses it on the thin metal sticker). I took a picture of the "Personal Lifetime Warranty Validation Sticker", and of the ser# plate, and included a picture of my license (license# deleted of course) to identify myself as the person named on the sticker. Voilah!, they honored the warranty and ok'ed me for service!
I purchased this amp around 1978, so I don't know if Sunn continued doing their warranty validation this way, but if any of you have the sticker I'm talking about on your product (with the information I mentioned), which essentially provides all the info the warranty card would, namely, tying your name to the reg#, I think you'd be in like flint!
Cheers!