Thanks for your advise. I will give a go and see what happens.
Just to share some more info with you. Firstly, power steering started to become stiff if I was getting over 30 miles speed, but if I shut off engine and start again I was getting normal power steering back until I would reach 30 miles speed again. It went like this for a few weeks until it became stiff all the time. Do you still think it might be the same problems you mentioned?