2000 Freightliner Century Power steering intermittent

Hey Guys ! New to this forum. I am a owner operator and mechanic on my own truck.
Today I started my truck after setting for a couple of months to move it for some maintenance that I want to do the truck. As I started to move forward , I noticed that the steering was very hard to turn, like no power steering. As i turned the wheel , all of a sudden the steering become easy like normal. I stopped turning and the steering became stiff again. As I manually turned the steering wheel back , the steering became normal again.
As I rock the steering wheel back and forth , there is no power assist then it would start working correctly again.
while the steering wheel is turning that direction. Every time I stop and start turning the steering is real stiff.
The fluid level is fine. Everything was working fine when the truck was parked. I did notice some steering fluid started leaking out of the top of the steering box , steering shaft seal. Could I have a steering box valve issue ? That is what it feels like .
any help for this owner mechanic would be appreciated.
Vic

 

My issue is not with lack of front end lubricant. I completely service my truck every 5k miles. The front end is all new. I did not have any issues when I parked it 2 months ago after a long road trip.
I will look at the resivoire filter and replace that and give it a try
Thanks for the tip
Vic

 

I will try greasing the front also but seems real strange that the steering was fine when parked.
Have used some Lucas additive in the system.
Vic