-88 560SL - power steering pump issues

Hi folks,
when I put my car into winter slumber in october last year, the were no strange noise from the servo pump. But, when I started the engine for the first time recently, a whining sound came from the servo pump. I used a stethoscope to make sure. The noise is constant, even after running for 10 minutes. There is sufficient oil in the chamber.
When searching online, I see many refurbished pumps out there, but it seems like they have not replaced the bearings. And, after looking at videos on youtube where they refurbish the pump, the bearings are not replaced.
So, is it not the bearings which cause the noise? I am a bit reluctant to buy a refurbished pump with old bearings.
Anyone with experience from this?

Thanks.

Rgds Erik

Hello Erik,

is the oil level of the servo system correct?

Hi Uwe,

yes, it is correct. Oil is from last summer.

Rgds Erik