EGR valve woes

[David in Hampshire]

Outback, 2008 diesel, complete with P0409

I've had the EGR valve out and couldn't find the carb cleaner.  M'sahib recommended oven cleaner and you know what, there's a lovely smell that follows you around!

Got tons of carbon out of the assembly but not all of it.  I have no clue if it's working correctly but I do know what has to happen next.

Take it out again and get the back off - tamper torq bolts and I didn't have the kit at the time.  Dismantle and soak until it's like new.  Squirt loads of carb cleaner down the J pipe and some into the inlet on the other side of the valve too.

Q is, how do you test it to be working?  As it's electric and not pneumatic, I imagine i'd have to put 12 volts across two terminals and the valve should open.  But here's where I get lost.  Any pointers?

ta, David