I'm glad you got it sorted out, and thanks for replying to say what the cause was. All these questions and answers will help other people with same type of problems.
We all learn things new, what might be obvious to some might be as clear as mud to others.
About ten years ago I had a problem with my speedo which wouldn't go over 30 MPH although I was doing about 60 MPH.
Nobody will guess why, but when explained, not only was it bazaar, but weird.