How doI open a Yamaha P120 to fix sticky keys?

I've had the very same problem twice so far. The only solution I figured is to simpy purchase an equivalent key (contact Yamaha service in your country for this) and to replace the broken one. The reason why the key doesn't work smoothly as the other one is not dirt therefore any cleaning won't help. The key is cracked deep in the place where it's attached to its 'axis'. So you'll need to remove all the screws and unmount the cover (it needs a sideshift to open once the screws are removed), be careful with the speaker wires. However you'll need firm moves anyway. Opening is tricky and gets me surprised anytime I do it so you'll need some courage :). Replacing the key is even more tricky. You'll have to remove the broken one by pulling it horizontaly (use some force, it's broken anyway). Placing a new key you'll need to uplift the 'hammer' and then slide a new one. I'm sure you'll figure it out once you see it with your own eyes (it's really hard to decribe but not so hard to do it). Hope you'll do fine. I haven't tried glueing the crack for I doubt it would work for long. Good luck!

There was a recall for a keyboard replasement for this kind of problem which was free, go to the oficial yamaha website and see if the recall is abailable I had mine done about 22 years ago

I have the same problem on my P120.
After a quick search on French forums, it appears that this is a known issue and Yamaha replaces the entire keyboard even if the warranty is expired.
You will not fix the problem by cleaning since the key is broken.

You should contact a Yamaha repair center or resalor in order to get a new keyboard (only keyoard not entire P120 !!!)

The process to replace the keyboard is quite simple and quick.

I will keep you informed as soon as I get my new Free of Charge keyboard to confirm ... and also with some explanations on the repair procedure.

Best regards from Paris

After contacting Yamaha Canada it will be the same procedure
they will replace the keybord(only) free

contact your retailer

After learning of this recall I contacted Yamaha customer support. Many of the churches in our district have the P120, my local church had two and they both had sticky keys. It is based on the serial number and after emailing a JPG of the serial number, my two qualified. Since I do most of the tech repairs for my district, Yamaha sent the two replacement assemblies to me - not the whole P120, just the 88-key mechanical assembly. I've been inside the P120 a few times so it was easy to do the swap, and in less than 1 hour per keyboard I had the job done. End of story - we now have two virtually brand new P120's.

Yes, this is serial number based. I was repairing one for a customer and contacted Yamaha, they said they sent a replacement keyboard to a specific repair shop for this piano previously. The shop apparently did not replace it at all, they just repaired the broken keys (and I assume kept the new keyboard) so this customer was screwed, the keys are much too expensive to replace so I had to make repairs, holding up well so far.