I'm a musician, with a degree in music technology. Professionally I'm a computer engineer, currently working in support, and I used to work at a shop where we would at least attempt to repair 'anything with a plug on it'. I've also performed repairs and modifications and built my own gear.
You will notice at the top of this page that it says "An independent forum for Korg product users and musicians around the world. Not affiliated with Korg". This forum is not an official support channel and whilst some Korg staff do post here, it is by their own will and they typically stick to answering questions about their newest products.
I agree this is terrible. If you're out of warranty, you may be better off finding an independent repair shop or technician. They do exist, but I have no idea how few or far between.Here inlies the first problem X-Trade. It's been nearly two weeks now since I left a voicemail message (during standard business hours) for my local Korg authorized service center regarding this issue & I have not received a call back.
Which country are you in? Have you contacted your Korg national distributor and they directed you to this service centre?
I do think forumers are even less able to help you if you can't get a reply from Korg or your service centre - unfortunate but true.
I do hope you can find an answer from them. I can only reccommend being more persistent - leave more messages, make more calls.