Elektrik: Flat Battery

[Beumers]

Hi all.
I found my car with a flat battery. After recharge again. Battery check was oké.
Amp test result 0,45 Amp current leak. I took out the fuses one by one and found the dash was faulty. Turned out the odometer kept on. Not all the time but when I tap the instruments cover in front of the odometer it flips on and stays on for a while. One time it stays on for days. The other time it goes black after a few minutes.
Did anyone experienced the same problem or semilar? It doesn't need to be a faulty odometer. There can be alot of causes.
Thanks Henk.

My car is a 735 1986.