The chain adjuster ring on my NC24 is seized solid, after nearly giving myself a hernia trying to unfree it and using copious amounts of penetrating fluid it just won't budge. I have tried the previous advice of lifting rear wheel in the air but still no joy. Anybody got any useful suggestions? Would getting some heat into the mechanism/hub housing help or am I likely to cause more damage than good ?

I take it you undid both the pinch bolts? Make sure there fully loose.

The NC30 has one pinch bolt and an outside adjuster, the NC24 has two pinch bolts and the adjuster is in the middle of the hub at the bottom.

Yep both pinch bolts totally removed and still no movement whatsoever. Currently using a long t-bar and getting enough torque to lift the bike clear of the ground but the mechanism just won't budge