Rev Counter Broken? 380sec Merc

[christopher.cross]

PLEASE CAN ANYONE TELL ME HOW TO GET MY REV COUNTER GOING AGAIN on my C REG 380 SEC IT SEEMS STUCK ON 2000 AND MOVES A LITTLE BIT. ANY HELP WOULD BE APPRECIATED I WISH I COULD FIND A DECENT WORKSHOP MANUAL FOR THIS MODEL?
MANY Thanks Chris.