Suddenly the steering of the car is extremely difficult?

Also, I have no automatic return of the steering wheel. I am basically driving this thing old-school strong-arm steering. I think one of the hoses has a leak in pressure or my pump. Is on its way out. The fluid seems a bit dirty to me, but the level looks fine. This isn't a new out of the blue problem.

A few years ago, I had a minor issue with the power steering. It was stiff to turn the wheel only during the cold winter months so I took it into the shop and they flushed it, mixed in some lubricant with the new fluid, refilled and sent me on my way.

Which hose, if any, do I need to replace or do I need to replace the pump and every single hose that goes with it? How easy of a job is it to do if I wanted to tackle this myself?