On my sx-KN5000 I have a key that is not playing a sound although strangely enough if I press the key right at the back end )nearest to the black cover it does sound. This points I think to a faulty key action. I therefore for want to open up the unit and have a look but I think it contains two capacitors which of course can hold a charge even when the mains is disconnected. I want therefore to discharge them for safety’s sake. But I do not know what they look like, what voltage they are, and therefore whether I can simply discharge them with a screwdriver or I need to use a resistor.  Can anyone give me any information or point me in the right direction.

I have tried to get this done locally (wirral) but there is no-one who seems to be able or wants to do it. there is an engineer in Surrey but sending the keyboard there is very expensive and difficult.