heehaw, I'm not familiar with your particular tiller, but in addition to the gearbox on top with the gear oil in it, there should be a cover, or shield, on one end (left end on all I'm familiar with) that covers either a chain drive or gear drive. Some makes and models have gear oil in that drive assembly and some use multi-purpose grease. My Bush Hog has the chain drive and the manual says every 100 hours to
"Remove chain drive shield and clean out old grease. If chain has one link or more of slack, have an authorized Bush Hog dealer resize the chain. Pack bottom of shield with multi-purpose grease to line shown in Figure 4-1 (about the bottom one-third and it holds about 2# of grease). Reinstall shield using new gasket."
I believe it's 14 nuts and bolts around the perimeter of the shield that hold it on. After the first 2 years, during which I estimated that it had been used at least 100 hours, I did that service. And then after 3.5 more years and probably 200 hours of use or more, I decided to do it again a couple of months ago. I bought a new gasket and grease, removed the shield, looked at it - everything looked very good - and I put the shield back on without doing anything to it or changing anything./w3tcompact/icons/laugh.gif I still have the new gasket and a couple of cans of grease and will check it again next year.
Of course, if yours has the gear oil instead of grease, then there should be a plug similar to the one on the gearbox on top to check and/or add oil.
Bird