In Australia (likely most western countries) we tend to get a bit lazy on the matter of specifications for our products. We place trust in our current supplier to make the recommendations on material that we should use for all manner of items in our final product. From grade and type of metal, PCB laminate, through to the paper used in our packaging and print material and labelling.
Typically we don't know the exact specifications that are being used in this case, often we don't care. "Leave it up to supplier X, they have always supplied to us and we have never had a problem. As long as we continue to buy from them everything will be fine".
It's a system that has worked flawlessly for years, even decades for some companies. We come up with the design concept, requirements and the supplier fills in the blanks and Viola! here is this fantastic product in our storeroom ready to send to another batch of satisfied customers. It truly is a utopian world that we are living in.
Until.. what happens when supplier X decides to retire, or goes out of business? You ask a new supplier (Y) to make the parts for you. They do so but it is not the same as supplier X, so we then proceed to blame supplier Y for shoddy work practices and being unable to get something as simple as packaging correct. Supplier X has done this for years without a hitch but Supplier Y is apparently incompetent. So then you try several new suppliers.. all apparently equally incompetent. You think somehow all those years ago you managed to find this magical supplier who is the only competent person in the industry and the only one that knew what you needed without being told.
Ok lets rewinds the scenario back to when you trialled supplier X. Possibly you were new to the industry an did not know what you wanted, supplier X gave you samples and you decided this looks good so lets go with it. Supplier X had no magical qualities, he was just first. Had you gone with Supplier Y then he would be the highly revered manufacturer in the future..etc etc.
The problem is not with the new suppliers, it is with the fact that you have not taken note of what supplier X has been providing and accepted purely based on his recommendation. You don't know what is being supplied, only that it works and looks how you want. Any other supplier will likely have different recommendations and so you receive different products. This is even more illustrated if you decide to manufacture offshore. The amount of times I have heard a customer say that the offshore manufacturer is incapable of delivering quality packaging, or print manuals or labels (these are the worst offenders because most companies don't regard them as needing specifications until they try to manufacture elsewhere).
We fall into the same trap of asking the supplier to "just do what he usually does" forgetting that most of his business may be targeted at a different country where there don't care as much about presentation, or most of his packaging is designed to be palletized and packed into a sea container not subject to typical airfreight handling.
If you want to continue manufacturing the same product in a time where local factories are going into receivership and cost considerations are pushing a lot of manufacturing offshore, then it is time to become a bit more intimate with your products, know every detail and stop asking for recommendations. Work on specifications only. If it isn't specified then get samples and find the closest match. Make that your specification moving forward. Time is well and truly here to unshackle yourself from an individual supplier and take responsibility for your own products IN EVERY MINUTE DETAIL.