I also had hard shifting at low speed such as in a parking lot or if braking and going is stop and go traffic. I had seen several posts about it and thought it might be "normal".

Today I went to the dealer for a check engine light ( I had checked the code at autozone first) so I asked them to check the transmission and do the harmonic balancer recall.

Anyway, the said I have a bad control unit (022-545-24-32-88 $598.00). I'm glad I purchased the extended warranty. My ML has just over 62K miles on it.

I have an appointment next week to get the repair done. I'm not sure if this requires a fluid change or not. If not, I think I'll have them do it at the same time.