I have seen several otherwise inexplicable glitches fixed by changing a hub and a decade or so ago I came to the conclusion that inexpensive or bargain USB hubs were neither inexpensive nor a bargain in the long run. On the other hand, there is no guarantee a new hub will fix your keyboard problem.

Before spending any more money my suggestion would be to plug the keyboard directly into the computer and completely disconnecting the hub.
  1. If the problem continues to exist then it has to be the keyboard.
  2. If the problem disappears when the hub is completely out of the loop, then it has to be involved in the issue.
    • Before getting rid of the hub try a new USB cable between your iMac and the hub, then if the problem still exists it is definitely time to replace the hub.



If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein