Does it say in your owners manual what kind of gear oil? believe it was thicker than 80-90,there was another thread on here not to long ago about this,we talked about it there,do a search.[seems like it was 140 something?]
Setting that clutch is tricky[if you get it to where it will slip if it needs to],try it in softer stuff first if you can,than just experiment.I know from doing it you don't need it very tight to hold and not slip in looser dirt,hit a stump this spring and that got me to thinking cause it may have slipped,just a little,so backed off the nuts maybe a turn or more,knew it would slip when using it next,and just figured I was going to have to retighten a little,BUT,it didn't slip,would stop and feel it every now and than,cool as could be,so...
Thing is,next spring,you should do it all over again.take it off tiller[drive line] if your storing tiller outside all winter,so's it don't rust shut on you.