tachometer

I just got a 2000 900ss I.e.. And the tach is not working ....when I start the bike it immediately jumps to 3.5k When I start the bike the tach goes to 3.5 k...if I give it throttle it goes to 4K and never goes beyond, but when I go over I go over 80 to 100 mph it goes backwards ...as I give...

Third time dashboard problem.. This is the third time ducati changed my tachometer dashboard and after 50 km look what happened for third time. At the same spot AGAIN. Please if anyone knows what is the problem inform me. I am so mad with ducati. 30000 euros for having all these trouble...