The acceleration time history should be a square wave, not a sawtooth. Acceleration due to gravity is a constant over time. The trick is to change the sign of gravity so it can be inverted in a fraction of a millisecond.
There seems to be something very wrong with your transient simulation. Starting from rest, the part should fall 2 mm in 0.02 seconds. Since the part is already at the bottom, remove the initial velocity so it starts from rest at t=0. Now change the sign on all the accelerations. You should see the part fall upward and hit the top stop in 0.02 seconds and bounce on the top for a while, then at t=1.00001 the acceleration changes sign and the part will fall down. It should hit the bottom stop at 1.02 seconds and bounce. I think the damping is adding a huge viscous force so it's like the gap is filled with oil and the part hardly moves at all in 1 second. Remove all damping and solve again.
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