5545 4X4 LEVER

Hi just got a tidy Zetor 5545 Tractor, she runs and drives ok but i can't engage 4 wheel drive,there is a lever by my left leg which goes up and down but does not engage the 4x4 drive,
Question 1 - is this the 4x4 lever
Question 2 - should it be up or down to engage 4x4,
Question 3 - does anyone have any idear what could be wrong with it.
Regards Dave.

Hi all,
I have had my 4 wheel drive working today,Pull the lever up for 4 wheel drive and down for 2 wheel drive, there was a spring on the lever linkage the needed adjusting,
Regards Dave.