The best thing you can do is bite the bullet and get a new/used amplifier. I got mine at a "European Car" junk yard in Seattle (Aurora Auto Wrecking) for about $45. My tach did exacatly the same thing.

Good Luck

__________________
Elliott Fager

1977 240D Hell Blau (Verkauft)
1981 240D Weiss (Gestorben)
1984 300D Dunkel Rot (Verkauft)
1982 240D Dunkel Blau (225k) "Panzer Wagen"
1981 300SD Beige (175k) "Kampfwagen"
1981 300SD Beige (205K) "Panzerkampwagen"