Santana 2000 Gls Board Problem 1993

Good to all, first of all I present me since I am new in the forum.
I hope you can help me with this problem in my Santana.
The problem is that the KM account of the board is not the total or the partial, worse if the velocimetro works and the counts turns, so it has me bewildered, I do not know what it can be. I do not know if it is mechanical or electronic the system
I have not yet disarmed it because I really do not see it easy to disassemble the board, I hope someone can give me a hand to see how to face the problem and see where the thing comes because I have no reliable way to keep control of the km that I am traveling to do it a correct maintenance to the car.

Thank you very much in advance.

SLDS.

Hello, the problem of yours is the clock changing it quietly for another that you solve everything, the theme is that the clock inside has some gears that are plastic and break so they stop walking or the other solution if you do not find clock is to take it to a house that is dedicated to repair them I hope I have been useful for a abrasion.