AFTER SEVERAL ATTEMPTS TO LOWER THE LANDING GEAR, THE PILOT ELECTED TO MAKE A GEAR UP LANDING. EXAMINATION OF THE NOSE GEAR RETRACTION AND EXTENSION SYSTEM FAILED TO DISCLOSE A MATERIAL FAILURE. THE EXAMINATION OF THE NOSE GEAR DISCLOSED THAT THE ROLLER ALIGNER ASSEMBLY WAS DISPLACED OUTSIDE OF THE CENTERING TRACK, AND THE NOSE GEAR RETRACTED INTO THE WHEEL WELL AT AN ANGLE. NO NOSE GEAR ASSEMBLY COMPONENT SHOWED EXCESSIVE WEAR OR FRACTURES.