resistors to draw 7 watts

I've just replaced my front turn signals from 21watt bulb fittings to LED clusters, unfortunalty these don't draw enough power from the circuit to trigger the flash correctly, i'm getting a very slow flash rate and no turn indication in the vehicle. When I reattach the bulbs it works fine so I know I havent fryed anything. I need to find a good resistor setup to simulate  the load the original bulbs would have had on the circuit, then wire the LEDs in paralel.

Could anyone with more understanding of Ohms law and didn't flunk math help me please.

John.

Cheers man. Just gonna try and find the Maplin equivilant over here in blighty.

Thanks again, glad to know im not the only noob to switch out his perfectly good turn signals with LEDs