I have a clavinova CVP-107 keyboard that still sounds good but makes a clunky sound after the keys are depressed and returning to regular position. I'm hoping that it may be corrected by replacing the felt cushion. Is this a difficult repair? Where would I get advice about repair?
Looking at the Service Manual (easy to find on the web using Google), disassembling and reassembling the keyboard isn't particularly difficult, though it might need a special tool (described as a "thin metal plate" in the manual) to remove the keys from the key frame. Note that you will also need enough "bench space" to take the complete key frame out of the piano and keep it somewhere convenient while working on it.
The hardest parts of the job will probably be (1) finding out where the noise is really coming from, and hence exactly what needs to be replaced and (2) getting the correct replacement parts at a reasonable cost. Personally I wouldn't recommend an attempting an improvised repair. It might not last long, and it could end up making the problem worse.
Most likely a professional repair shop would just swap the entire keyboard for a new assembly, and send the old one back to Yamaha for refurbishment or recycling. That is cost effective, since the average customer won't want to pay for the labor costs of a "one-off" repair job unless it's something obvious and straightforward like a single broken key, and it avoids any lingering disputes and/or bad feelings about whether the repair was done "properly" or "as well as it should have been". But the downside is that it limits the availability of individual parts for people who do want to do all the work themselves.