1100i rev counter

Gents Any advise on what and how to check what’s stopping my rev counter working??? I think it’s driven from a sensor on the top of the left hand rocker cover does this some times play up?
It normally flickers about at about 500 but then very 1000 miles or so it goes up to 3000 for a minute or two but just sort of flickers never really looks like it’s reading anything

rev counters are renown for struggling to read if the voltage is low or excessively highmight be an idea to check your charging system with a volt meterif its drive on from the crank or cam position sensor ( and the bikes running fine) check for loose connections then if still problematic run a temporary earth from the rev counter body to the block… after that replace the rev counter