Can EGR vale be cleaned, how do you know its totaly shot..?

Hello all, I'm new round these parts but delighted to have found this forum !!

I've got an 04 K12 diesel van that has an EGR with a bit of trouble, namely spewing out grey smoke and stalling and jerking on acceleration and ascending gears, its in the garage now. However I don't think they are too familiar with this make or model, a new EGR willl set me back a whooping € anyone know if it can be cleaned/ fixed or what are the cardinal signes that its well and truely ######ed...beyond rescue, bear in mind I'm am not a mechanic so if you can explain like I'm a 3 yr old that would be great fwn
any help or suggestions from the micra massif would be brill , thanks !


I cleaned the EGR on my Avensis Diesel.

Removed the EGR from car, brushed out what carbon I could and then cleaned the rest out with Carb/ Injector Cleaner and turps.

Think I'd use my ultrasonic cleaner now if I'd have to do it again.
Thanks Hugh , mechanic did that, it was fine for a couple of days then, started sticking as bad as ever.. Any suggestions, are these things available second hand, or is it wise to just buy new altogether..?