In this situation, I used a zip tie to secure the keys on an SY55: drilled a tiny hole through the key and used a zip tie to hold it to the chassis. The repair is permanent, sturdy, and the key behaves exactly the same as its neighbors.
|notice the zip tie just visible on the Bb key|
|the other end of the zip tie is in a washer|
On the VK7, the bushings tend to wear down, and the keys slide off. Buying new keys doesn't help much, and a new keybed can be pretty expensive. Zip ties between the keys work flawlessly at straightening the keys out, without adding any interference or resistance, and keep the keys on the bushings.. Plus, the metal casing around the keybed makes it impossible for the zip ties to fall off or move around. This is a great, permanent, and effective repair!