Sounds like you need an excuse to break her down! So, since you have run it, it must have gotten dirty right? Must be time to take it apart and clean the bearings. Start off easy, and clean the carrier bearings. Take off a wheel, pull the hex off the axle - being careful not to lose the hex pin that goes through the axle - then remove the two kingpin screws holding the carrier to the C-Hub. This will expose the two bearings in the axle carrier. Take them out, but them in a small container with some WD-40 and shake it around for a while. When you think they are clean, dry them off, lube them with some good bearing oil (or alternatively Tri-Flow, its good stuff) and re-assemble everything. Now do this to all 4. Cleaning your bearings regularly will extend their life considerably! Have fun!