I recently asked a member in the repair forum if his goal was to "make it tick" or "return it to grade". I then gave a very brief explanation of what happens when a balance spring is altered in length or the mass of the balance wheel is changed to "fix" an altered spring. This was followed by the discussion here on cosmetics and chronometers; restoration vs. conservation. In my opinion, whenever alterations are made that deviate from what is found (this includes repivoting, detent replacement, changing mass on the balance, etc) it should be documented (under the dial). This is for two reasons: first there are times when it becomes important for historical reasons to distinguish between repairs and original work. Secondly, especially with the escapement or balance assembly, alterations that are not readily apparent may and do hinder the work to return the piece to its proper function (which ultimately means performance as a timekeeper). As for conservation/restoration/repair, I think that up to the owner. I do not even redo work that is obviously non standard (globs of solder used to secure the escape wheel to its hub) without checking with the owner. There may be a story connected to that which is important to them. What do you with a timepiece that someone used to survive but they repaired using what was to hand? Do you return it to factory standard or conserve it as is? It depends on the story the piece wants to tell.