PAL Airlines flight 1922, a DHC-8-300 aircraft, en route to Deer Lake, NL (CYDF) with 47 passengers and 4 crew onboard had an indication of a potential nose landing gear issue. At 10:57 local time, during the approach at Deer Lake, the flight crew selected the landing gear down; however, a weight on wheels caution light as well as advisory lights illuminated, indicating that the nose landing gear was not in the down-and-locked position. The flight crew executed a missed approach and entered a hold in order to troubleshoot the problem. At 12:02, the flight crew requested a diversion to Stephenville, Newfoundland and Labrador, and declared an emergency. At 12:30, the aircraft landed on runway 27 at Stephenville with the nose landing gear in a partially extended position. On touchdown, the nose landing gear fully collapsed, and the aircraft nose structure came into contact with the runway surface. The aircraft slid and came to a stop approximately halfway down the runway. There were no injuries to passengers or crew. Findings as to causes and contributing factors: 1. For undetermined reasons, a previous repair to the inner cylinder of the nose landing gear shock strut was not designated with a specific permanent marking as required by the approved component maintenance manual, resulting in the installation of a standard size bearing where an oversize bearing was required. 2. The reduced sealing force caused by the smaller-than-required bearing installation likely allowed the nose landing gear shock strut to leak. 3. The reduced hydraulic fluid volume, in addition to a possible nitrogen leak, reduced the internal static pressure of the nose landing gear shock strut and allowed it to partially compress when it was in the up position. 4. The airflow encountered in flight when the nose landing gear was lowered further compressed the nose landing gear shock strut and allowed the tires to impinge on the aft landing gear doors, thereby jamming the nose landing gear in a partially extended position.