Tacho problems

[PGAHOWELLS@domain.elided]

Hi
My Tachometer dropped to zero twice during a ten minute drive this morning. It
remained at zero for 0.25 of a second and flew straight back to 3000.
Tonight it dropped back one  second after starting and remained at zero for
500 meters, and then suddenly jumped back to 2800 or whatever I was doing.
The engine is running OK
I remember a suggestion this Tacho problem could be bad fuse. If it is not
that does anyone have other suggestions.
Peter H