Update: bought muti-meter and connection at point were you insert bulb has power surging through it but still no light on the indicator bulb. I;ve tried renewing bulb (checking the correct voltage and wattage 12V/21W). It appears that when I insert the bulb the power disappears, disconnect bulb and apply multi-meter and I have a reading again. Logic does not appear to apply with this situationa nd any help or guidance would be very much apprecaited. In advance thank you.
Noel.