[Saudade]

First of all, are you sure it's the PS pump? Bubbling would indicate air but how did it get in there unless the shop disconnected the lines. To bleed them, start the car and turn the wheel from one extreme tot he other and back. Repeat and few times then check the level, fill as needed. Continue until no bubbles present.

Did you check your belt? The serpentine belt is a bear to adjust. It's possible it's a bit loose and turning the wheel puts a load on the PS pump and makes the belt slip a bit.