Power steering gurus,

Had the power steering on my fuego 4x2 '97 checked last week because it was relatively heavier to turn, the PS humming and the lack of the wheel to return on the center position when turned than the other pickup (same model)I drive and the occassional humming and rattling when cornering. Here are the stuff the mechanic did and my queries:

1.) Disassembled Steering Gearbox. Ok pa naman daw so it was rebuilt with new steel balls and ATF for the clunking sound which was somehow minimized after the procedure. Wala daw bleed screw on the gearbox?

2.) Checked steering pump check valve for the humming but still it's there - air in the system maybe? Where to bleed?

3.) Replaced worn out Centerlink(555), Idler(555), and steering coupling. - How do you tell original japan three-five/555 from taiwan knock-offs? I found 555 idler with protruding and flat nipples (OEM is ungreasable and has flat, sealed surface on the "nipple" part) respectively tagged at 2.5 and 2k pesos, no boxes and both have the same labels on the plastic and 555 markings on the parts themselves. Which is orig?

4.) Removed old OEM TOKICO steering damper as I suspect it contributes to the heavy turning. Now I'm temporarily driving within the city without the steering damper on the centerlink and the wheel turns much lighter but doesn't return center. Which of the steering parts does the returning-to-center of the wheel from the turning? Any long term effect if I delay my reinstallation of the new damper?

Any opinion and advice from the experts will be greatly appreciated!
TIA