Hello...............I'll give you an answer instead of a sermon....................

You might just have a loose connector or wire inside where the keyboard pad connects to the circuit board. Most keyboards I've seen only use two connectors (4-8 wires each) to cover all the notes. It sounds like 1 connection is not being made, hence every 6th note not working. I've seen this before..........it's worth checking out before assuming it's a component problem Good luck. -charley