ive read all the threads about fixing the cluster (resolder cracked connections etc.) every 7.7 miles my speedo flops left to 0, right to the peg and then back to the speed im driving. meanwhile the odometer disappears, for 3 secs,then reappears at exactly 7.7 miles less. It has been doing this for 2 yrs. in exactly the same way. I went to the dealer and got the blah blah about replacing the cluster. Help

 

I think you do indeed need the cluster replaced.
There is an internal counting fault.
The most you can do is the dealer HEC test and see what the results are.
I'm sure they may already have done that.
They don't normally go in and try any of the things we might do unless their service info tells them to do so..
The HEC testing is accessed using the reset button to trigger the test mode, then you step thru the functions and see what the results are.
You need info on how and what you see for results and there is a lot to it to try to show here.
Maybe some one will post a link.