I think i have worked out my problem with my tacho and i need a 390 ohm 1 watt resistor but i cant find them at all
Does anybody know where i can get one from?

Thanks
Tommy

Maplins will sell you a 390 ohm 2W resistor for 18p. As long as it will physically fit (i.e. there is enough room) then it will do just fine.

Bluebell Audio has 1W 390R

Here