Diagnosing Faulty Indicator - GTi

[nic78]

I spent most of today removing my front bumper and putting in my new sidelight (the actual headlight housing, not just the bulb) and I thought I'd have a go at fixing my temperamental indicator (the indicator underneath the xenon bulb). The indicator started flashing quickly a while back, so I knew one of the bulbs had gone, but after a week it was fine, and only yesterday it started doing it again.

After fitting the headlight I went to tackle the indicator. I realised that I didn't have the diadem bulb, the one with the blue tint to it, so in the end I left the original bulb in. I checked the filament in the original bulb and it looked fine. However, once I had put the bulb back in, I put the right hand side indicator on, and the bulb wouldn't flash at all, whereas before it would flash every now and then.

My question is, how do I know whether it's a faulty indicator stalk or a fuse/relay? I really don't want to have to remove my bumper again to change the bulb.

Thanks for any help/advice.

Nic