I have a 2005 926004 with the differential that manually locks with the handlebar lever. Six years ago, the shop replaced the differential and right axle because the splines on them had stripped. The drive failed this year and I’ve discovered that the differential spring has failed. I am going to replace it myself this time and want to know if I should pack the differential with grease before installing it. If so, does the diff need to be regularly repacked? Is not greasing it why the spring keeps failing? I ask because there is no mention of this in the recommended regular maintenance.