psandhu

those shanks/teeth look like they are about 8" long. to me, theylook too long and too thin. when you operate it, there is probably too much leverage/torque going to the the point where the shanks are connected to the I beam.

could you get ahold of some railroad spikes and use them instead? i can find them for free when walking along railroad tracks. weld/bolt them on so that only 3-5 inches max will be digging into the ground. put 3 or 4 of them on the front of the I beam and 3 or 4 offset from the front row into the back row. the first row will break it up somewhat, the second row will break it up even more. that's the way all the smallercultivators that i've seen are arranged.