Casio CT-6000 Keyboard Vintage MIDI 61 Key Power Cord 1984

Description

This is a nice unit considering it is 30+ years old
Needs a clean/dusting
I turned it on and the settings/options work
The keys function....except as noted in picture
4 do not make any noise...2 black and 2 white
The one white key makes noise but it is quieter than others
Look at yellow post it note.....
I don't know how to fix those keys...dust? Don't know!!!
I really don't want to ship this because of the size and weight.
However....I am not ruling it out either
Ask questions prior to purchase....
I will do my best to answer them
Thank you