That's the split gearbox one isnt it?
make sure the spring guide is correctly seated in the back
tappet plate needs to be connected correctly and everything else is fairly self explanatory
If it isn't the split gearbox, it's almost definatly your anti reversal latch getting in the way, just persevere with it
spring on the cocking handle sprain easily, just get hold of a new one (make sure it's the right one) and be more carefull next time, or just leave it off, I do on the ones I have sprained and you don't really notice.