Hi Ian,

WOW !! That is strange

So far every upper end PSR from the Y2K that I have seen or played has had that same slightly lower C-6 key.

Mind you it is not off by much , and most people would never see it , but none the less it is there.

I would say 1/32" to 1/64" of an inch lower than all the rest of the white keys.

The PSR-640 and 740 were ok , it started with the Y2K.

It really is nit picking , I`ll admit , but it is there.

If yours does not have that problem , then you truly do have a one of a kind !!

Take care my friend , and you are most correct , I am no closer today than I was 3 months ago.

Later ,
Gary