I've been topping up my power steering every 4-6 months for a little while now. Not much extra fluid needed, but enough to cure the "yowling" noise it makes from time to time. Adding fluid cleared it up every time previously so I assumed I had a very slight leak from a hose, however...

Went to move the car today and immediately had the noise as soon as I moved the wheel, but upon checking I found the fluid level to be within normal bounds in the reservoir. Does this likely mean the pump itself is going out? I don't want to overfull things so I haven't aded any fluid.

If so, looking at replacement pumps doesn't turn up much. I'm assuming I need part number 0024662201? Is it the same part for the E320 of the same vintage?

Pelican only has a new one at almost $1000! which is too steep for my old nugget. Normally they would have an OEM replacement, but nothing's coming up.

What are my best options -
- remanufactured quality brand like Bosch?
- another third party
- used original part from the usual suspects?
- something else?

Thanks for any and all suggestions!