top octave of piano is

I tune my Yamaha 5'7' grand every 4 months. I'm usually very pleased with the result, but recently the upper register has sounded flat a few weeks after tuning. It's 20 years old but I play it every day. Great instrument!

I'd like to brighten the tone in the upper register, and of course that's exactly what I'll tell my tuner, whom I've known for a long time and who does a very good job.

Any advice on what else to ask or to look for?

In my 'real' life I'm a Family Doctor who is driven crazy by patients who bring in sheafs of printouts from the 'Demon' internet. I hate to do the same to my piano tuner, but this forum has so much wisdom I can't resist!

Regards,

Have your hearing checked by a medical professional. Seriously, Yamahas in that size range tend to be intolerably bright. If it doesn't seem so to you perhaps you are developing a hearing problem that should be investigated by a member of your own (medical) community.