When you did the fluid change for the transmission, did you use an OEM quality filter? And fluid?

And, maybe more importantly, when filling with fluid:
Did you fill until it was dripping out, cap it, run it through all of its gears, re-open and re-fill until it was dripping out again?

If not, your fluid is too low and it will knock when you turn and push it. The correct amount is something like 6 quarts of ATF.