RD-300GX keys sagging

[Terry W]

My 300GX is about 15 years old and a couple of the keys (E, F, F# in center of the keyboard) are sagging a bit. In addition, sometimes that E plays but does not sustain when held down (but it does sustain with the pedal).
1. Is this something a competent DIY guy could repair himself?
2. Where's best place to get the parts?
3. What could cause the E key sustain issue?

 

[Biggles]

1 yes
2 depends in which Country you live and any exorbitant tariffs that may apply if having to import
3 may be a sensor issue so check wiring off the key