Keyboard has silent G's

by Dianne
(St.. Thomas, ON Canada)

I have the opportunity to take my Mother's Yamaha keyboard . It is the YPP-50 model.

I noticed that every G on the keyboard does not work.

My brother, who has had this in his home said that they were all working recently when he tried them.

Of course, we couldn't sell it as it is. I was wondering if it would be worth it to take if it is something that could be easily and inexpensively repaired.

I know this is an older model and perhaps it would not be worth fixing. I wanted it for my own enjoyment and for my granddaughter.

Can someone give me some idea what I may have to do to repair it?

Thank you