See, Flying Camera, this is the situation I was trying to parse: I am NOT talking about a lens possibly breaking after a few days or even after a few years with heavy use. The work I did did NOT weaken the structure. I am talking about a lens that, IF MY VERY LIFE DEPENDED UPON IT, would work as well as one new, and as long. It is so difficult to ask people to speculate upon THAT VERY HYPOTHETICAL POSSIBLILTY because the mere mention of 'working on it without being a professional' conjures de facto ugly possibilties. (Just like the time I was at a flea market in a children's school on a weekend and I casually asked to use the restroom (at 63, nature calls often!): the horrified looks I got were genuinely priceless and it actually took me about five full minutes to understand why!) Again, I would bet my very LIFE upon that lens' integrity.
However, Flying, your point is well made in that THAT argument I posed really does not matter in, at least, a theoretical sense: Irrespective of the functionality paradigm, buyers, indeed, can also be expected to have a RIGHT to know about its innards (if only to avert shock from a future repairman).
But...can you respond to this: if you had a lens that you had bought from someone else long ago, say anonymously at a flea market, and did not know that it had been serviced previously by a nonprofessional, would you be obligated, morally, to 'disclose' such. This would mean that, at least potentially, every person who sells something has an obligation to open each item and inspect it for this very occurance in order to 'cover' for the potential of the previous owner's possible malfeasance. I do not think that too many do this. In my opinion there is a marked difference between nondisclosure involving 'selling fuctional integrity' and 'selling dubious functionality that appears to be functional', even though it can be argued that both lack disclosure and both can be adjudged 'wrong'. However, there is a weighting required here in order to assess a proper moral value.
My argument begins and ends with the utter assurance that the article in question can withstand the rigors that a virtually new article can. It does not take into even reasonable possibility that it will fail. (To NOT disclose such would be abhorent to me.) But, FlyingCamera, assuredly, I do also see your valid and important point. However, I wanted to assert my assurances (those averting the potential for failure) within my hypothetical argument. That dichotomy easily (and conveniently, for some) gets waylaid. - David Lyga