Hi David, this is most likely a lose wire, so I can find an engineer in your area can you provide me your post code?
I just wanted to follow up and check if you required any further assistance?
Apologies for the delay in getting back to you, I would suggest you use Lewis (07939 212458) who is a very experienced Keyboard engineer, and comes recommended from a number of other customers who we have referred to him in the past.
Lewis is currently on leave until next week, but advised due to the complexity of the Tyros it needs to be taken apart in a workshop, he is however happy to arrange a suitable time to come to you and collect it and then drop it back off.
He charges £35 an hours for repairs, he estimates it will take about 2 hours.
Please let me know if I can be of any further assistance.