Welp... 1990 legacy wagon. There's a vibration happening when I turn the wheel to the extreme (left or right). Imagine a purring sound but a vibration. IS something loose and/or something worn out?

Check to see if the fan belt is tight, and in good shape. Also, check power steering fluid to see if full.

 

It is possible that the p/s unit is going bad. I had that happen on a 91 Subie, when the unit decided to disassemble itself. I bought a replacement unit from a wrecking yard for $35. It swapped in easily, and worked great.

also, look in the tank while idling for foam/bubbles. Could be the suction line is sucking in air.

there have a crack rubber boots on the rack pinion...there have a leaky?

i think Rooster2 and 1 Lucky Texan is right.