Thanks for the comments. Dog, what was the value of the single load resistor you used and could you draw a basic wiring diagram to show which wire to connect it to? (I don't have a manual yet.) As mentioned, I have 4 individual resistors but they're quite chunky and would rather just have the one.
resistors:
http://www.oberon-performance.co.uk/acatalog/LED-Resistors.html
indicators:
http://www.oberon-performance.co.uk/acatalog/motorcycle-indicators-led.html

Thanks again, neill