Whilst doing various other bits on the engine I thought I'd check the EGR valve.
After removing it and managing to extract the rusty screws holding the motor section on top, I found the plunger pretty much stuck solid.
It took a lot of force to get it to move at all, the first time & the movement through the full travel was rough.
I've flooded it with inlet cleaner and soaked it in light oil overnight and the movement through the range of travel is now completely smooth - but it still takes noticeably more force to start it moving off the seat than to move it the rest of the way, as if it's wedging in a taper when closed?
Does anyone know if this is normal, or is it just worn out?