1*2 xenon issue - ignitor/ballast/bulb ?

[Or172]

So , The xenon bulb most of the times isn't working but sometimes it's turns on for a few bits , Sometimes it's blinking.
I'm not sure which of the following cause the issue : Ballast / ignitor unit/ bulb
In case it's the ballast - Is it fine to buy the cheap ebay one?
Thanks!

 

[Or172]

bump

 

[Vaughan]

So swap parts over from the other side that works...