| nsk bearings are a better quality (french) aftermarket bearing so must have been replaced before, flush them out with fresh fuel & inspect for damage or play
as for seals if you pop one out you will find most industrial supplies stores will keep a seal to suit tho they may look good they could still leak or be brittle
everything else is fairly simple (arrow on piston pointing toward the front of the engine) just relube each moving part with some straight 2 stroke oil as you assemble
i myself use a dab of engine assembly grease & 2 stroke oil on all internal seal bearings & just oil on the bore & rings | 
