Carver heater, failing elec auto ignition.

Hello again
2007 Nuevo.
I have had a few queries lately and somebody always kindly assists.

The carver space heater auto ignition (click sound) in my vehicle has recently become temperamental, sometimes it clicks/works other times nothing at all no matter how many attempts I make. When it clicks the fire starts up no problem.
I changed the battery and cleaned the contacts in the auto ignite unit but it still only works sometimes.

I am thinking its either the auto ignition little brown box unit that's failing...or... whatever sends the 'message' to the auto ignition box unit to start firing is not sending that message.
I realise that this 'message' is triggered outside the auto ignite unit and operates as soon as the gas dial is turned on the top, perhaps it's located at the base of the internal on/off vertical rod? 

Has anybody have a similar issue or have a check for this, hopefully it's just a poor contact somewhere?

So before buying a new auto ignition box for about £100 (wow), please has anybody got a test.  I hope it's an easy fix, a long shot I know.

Thanks again
AngB

You could try examining the HT lead from the magic box to the sparky igniter ( the 'spark plug' at the gas burner end) for a short to earth. Also check the spark igniter gap isn't too big, and that it doesn't have a carbon build up shorting the spark to earth.