It could also be the ribbon cable that attaches the keyboard to the dock itself. I have sent one off for repair and it came back with tape over the ribbon cable. this worked for a bit but is by no means a permanent fix.
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=== Update (07/07/2017) ===
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Actually just repaired my keyboard. the solder joints are loose on the flat ribbon cable connector that connects the keyboard to the dock. re-soldered the connectors across that pin and its working like a champ now. hope that helps.
It could also be the ribbon cable that attaches the keyboard to the dock itself. I have sent one off for repair and it came back with tape over the ribbon cable. this worked for a bit but is by no means a permanent fix.