306 on the circuit board will refer to the component number on the circuit diagram - the specifications for the capacitor will be written on the body of the component itself...
Capacitance value in micro Farads uf
Voltage tolerance - higher is fine but never lower
Temperature rating - 85 is normal 105 for high temperature places.
Also some capacitors are polarized - must be put in the correct +/- way round.
If in the UK shops like Maplins will sell what you need - if in doubt unsolder the capacitor and take it into their store.
Peccavi, February 2013
