But the next person to get it, might not know because every chip doesn't have an individual history, at least not anymore for my colection.

So it's nice to tell the buyer that it was flattened, but don't expect the history to continue past there.

Without a long debate (hopefully) restoration of an original chip, without alteration, shouldn't be a problem. Like cleaning...

Now what about restoring holes, maybe someone will figure out how to replace the hot stamp on a chip, or remove a cancelation. That is a problem.

I guess there is a line somewhere, but it's going to take a laundry list to say, cleaning is OK, straightening is OK. Filling holes, repairing HS, or removal of a overstamp, are not. (just some examples.)

There are degrees of change, so it's got to be a complex answer to a complex question.

Personal view, cleaning or un-warping, is not alteration. Adding or removing features is an alteration or restoration and should always be disclosed.

I've never done any experiments of chips, but for records, two sheets of glass, in the oven, does a dandy job. Remember the label section is higher than the grooves, too much wieght and the whole thing goes flat.

Unwarping a chip, without distortion appears to take a gentle touch. I'm not going to try it unless it's a research project. My warped chips will still be warped, until some safe method is perfected.

Thanks for the report Sheldon, glad you had success.