A CRJ700 RETURNED TO THE DEP ARPT BECAUSE THE FLT CREW WAS UNABLE TO RETRACT THE NOSE LNDG GEAR. FOUND NOSE STRUT ASSEMBLED INCORRECTLY.

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REF LOG PAGE PIREP ('GEAR DISAGREEMENT WARNING MESSAGE ON TKOF WHEN GEAR SELECTED UP; FOLLOWED BY PROX SYS FAULT #1 STATUS MESSAGE'). ACFT RETURNED TO FIELD IN ZZZ. AFTER JACKING THE ACFT; IT WAS DISCOVERED BY THE CREW THAT THE NOSE LNDG GEAR COULD MOVE 8-12 DEGS L AND R ON THE CTRING CAM. WITH THE NOSE GEAR NOT CTRED AND THE GEAR HANDLE SELECTED UP WOULD CAUSE A DUPLICATED DISCREPANCY. UPON REMOVAL OF THE NOSE LNDG GEAR PISTON/AXLE ASSEMBLY BY THE CREW IT WAS DISCOVERED THAT THE UPPER BEARING WAS INSTALLED INCORRECTLY. IT WAS FOUND THAT THE BEARING HALVES WERE INSTALLED WITH THE METERING GROOVE INSTALLED OVER THE RETAINER RING; VERSUS THE RETAINER RING GROOVE INSIDE THE BEARING HALVES THUS NOT ALLOWING FULL EXTENSION OF THE NOSE LNDG GEAR PISTON ASSEMBLY AND FULL ENGAGEMENT OF THE CTRING CAMS; ALLOWING THE PISTON/AXLE ASSEMBLY TO MOVE TO A FULL EXTENSION WT OFF WHEELS. UPON INSTALLATION OF THE PISTON AXLE ASSEMBLY WITH A NEW UPPER BEARING AND RETAINING RING IN ACCORDANCE WITH CRJ AMM BECAUSE OF THE AMM NOT DESCRIBING WHICH GROOVE TO ALIGN THE RETAINING RING OR WHICH GROOVE TO AVOID; IE; THE METERING GROOVE. THE CREW ALONG WITH ZZZ SUPVR DECIDED THAT A SECOND SET OF EYES RII WOULD BE GOOD FOR THE BUILD-UP OF THE PISTON/AXLE ASSEMBLY. REF THE PISTON/AXLE ASSEMBLY INSTALLED AND SVCED AT FULL EXTENSION; THE NOSE LNDG GEAR CTRS NORMALLY WITH NO MOVEMENT.