I purchased a Kubota rototiller in 2005, and have had some mechanical problems with it. After hitting a superficial tree root, the gearbox pulled off its mounting bracket. The shear bolt broke, but not before the damage was done. The problem is that the sheet metal on the top of the rototiller is too thin. The 3/8" mounting bolts pulled right through the sheet metal!
To solve the problem, I welded a metal plate under the sheet metal and up-sized the mounting bolts to 1/2". With the mounting hardware beefed up, it should be good to go.
When the gearbox broke loose, it also broke the chain housing seal, and the inner rotor seal - bummer!

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