I just bought a Model M SSK keyboard that I suspect was originally from some junk shop on Taobao. It came to me with quite a number of missing rivets already, but seller (a GHer) had assured me it was working fine. When it reached me I heard a rattling sound and after testing the keyboard, found the arrow keys not actuating at all.
I opened the SSK to find another two rivets had popped out. Most importantly, there were no intact rivets on the bottom right of the keyboard (when looking from above ie at the key legends). In other words, there were no intact rivets below the arrow key cluster.
I do not have the ability to do bolt modding, and am definitely going to return this to the seller. I’ll file a complaint if necessary. But most importantly, I’d like to take advantage of this opportunity to learn something. How we can tell that something was glue modded, or a frankenboard, or anything. What should I look out for? Is it possible that the keyboard was already flawed and the seller stuck the rivets on with superglue and hoped for the best, or was I merely unlucky that whilst in transit to me, two crucial rivets fell off from the area that had already lost most of its rivets?
The fact that nearly all the rivets are intact on one side and nearly all are lost on the other side of the keyboard has raised my eyebrows. Did this keyboard sustain a bad fall in the past? There is a piece of broken plastic inside the right side of the keyboard, but the external casing is reasonably intact with more scuffing on the right side than the left side but no obvious cracks. Nothing I would consider significant damage.
I am trying to determine whether seller is honest but unlucky, or dishonest. If the latter, I am going to escalate to a dispute immediately. For now I am assuming the first.
Here is a photo of the disaster area and another photo from the left side of the keyboard. If I work things out amicably with the seller I won’t show the identifying sticker on the center. In any case I don’t see anything that appears out of place but I don’t know what to look for. The two dropped-out rivets look no different from the other rivets that fell out of my other Model M terminal keyboards. IE there are no obvious signs of hot gluing.
Finally, let me add that I have some IBM Model M122s and 139xxxx 101keys. All of them have lost at least 1 rivet, but there's no sustained pattern - eg none of my other keyboards have all or most rivets lost from any single area. The fact that this keyboard has so many rivets lost from one side really perturbs me.

This is from the left side of the keyboard, ie the part under wasdzcx etc.
This is from the right side, ie under the arrow cluster.