Yamaha P-45B Digital Piano (please read)

It had been working fine until one day all the D and G sharp notes in the lower octaves stopped working. I opened it up and gave it a dust out but its still doing the same thing. Maybe someone who knows about electronics will be able to fix. Cost about 400 new. Beautiful instrument. Full size 88 weighted keys. Stool and stand included which probably cost about 50 aswell. Pickup in Letterkenny fixed price please call if you're interested thanks