The unfortunate thing is the number of broken rivets is the hardest thing to see in an e-bay sale, but has the largest effect in the usability of a keyboard. I doubt even asking a seller will get any sort of response.
Unfortunately, I've only got socket head 4-40 screws right now, which have heads that are too tall to repair the first row of rivets. I'll try and get some that are low enough profile sometime this week, and maybe post a guide on repairing them (tho I know there are others already on the net).
The yellowing is very minor, and I didn't even notice it until I had the top half of the case off, and was washing it under a faucet. The pattern is very strange, and only extends about 1/4" from the keys.
The oddest part is that the keys are all 1 piece, except for the F and J keys, which are two piece. I suspect that means that the majority of the keys are actually replacements, and not original. I've never seen a keyboard with a mix of 1 part and 2 part keys.