During the initial climb after takeoff, the pilot reported that when the gear was retracted, there was an unsafe gear warning. After several unsuccessful attempts to correct the condition, including recycling the gear four times, the flight diverted. Although the pilot had down and lock indication for the three gear during the recycling, after the fourth cycle, there was no gear indication, despite attempts to extend it using the emergency gear extension system. The pilot did a low pass over the airport where air traffic control personnel confirmed the nose gear was not extended. The pilot subsequently landed nose gear up. Examination of the nose gear assembly revealed the nose gear shock strut was collapsed about three quarters of an inch from full extension, which prevented the strut from engaging the uplock during retraction, and prevent the deactivation of the unsafe warning during extension. It was also determined that the partially extended strut could improperly contact the uplock, restricting the movement of the strut. Further disassembly confirmed the incorrect installation of the two internal seals, which would prevent the strut from extending fully.