Hi When you dismantle you keyboard the Keyframe is part of the top case if you can try not to disturb the connections as the type of connections that Technics have used are great if they are not disturbed too much, any tarnish that has formed can cause the processor to read as a fault and will stop the unit from working. If I remember you should be able to remove the contact boards without disconnection and then gently fold them out of the way, letting you gently unmount the key sets and feed them out of the top case.
wishing you luck regards John.