I've done this a number of times with Roland keyboards.

Firstly the keybed unit is removed. The only electronics to be worked with is one or two ribbon cables which attach to the keybed. Once these are carefully removed the keybed can be dissembled from the casing.

Next the plastic keys are removed one by one. These are held in place by a spring at the back of the key. Once the keys are removed there is a grey rubber strip spanning approximately one octave. These can be gently removed and the contacts cleaned.

Once cleaned everything is replaced in the order removed.

As has been said above - if you are not comfortable with this sort of operation let a technician do it - that being said I have done this a number of times on my Roland keyboards and it isn't too difficult. The problem with Rolands keybeds is that the row of contacts is no completely airtight and in time dust gets between the contacts and circuit boad creating dead nots or alternatively notes at full velocity.

A google search on 'cleaning Roland keybed contacts' may reveal a complete article with pictures of the operation. I know I saw it somewhere but can't remember now where it was.

Kevin