Focus LT Speedo Issue

[GT88]

Hi, We have a 2007 Ford Focus LT CL. I have noticed a few times that the speedo plays up. I just got back from a drive and the speedo was about 20 kmph more than what it should be (ie was displaying around 80 kpmh when I was driving around 60 kmph). When I turned off the car the speedo was stuck at just below 20.

I have noticed this a few times in the several months we have owned it. When we got the car, the indicator ticking sound wasnt working and the dealer sorted it out and said they had to replace something at the back of the cluster. Not sure if this has contributed to the issue. But most of the time it works fine. Just the odd occasion where it plays up.

Any ideas?

Thanks.