Just bought an 84 300D-T and it is making some nailing like noise (never had a diesel so not positive that is what it is.)

Anyways - was going to do an adjustment... the instructions in my book say to hold the adjusting nut while loosening the lock nut. But it doesn't say which way to turn the lock nut to loosen. I assumed clockwise so it would be moving down compressing the spring but it wouldn't move with quite a bit of pressure and I didn't want to break anything. Is clockwise the correct direction?

Thanks,

Ed