It could be low on fluid or have a packed filter. it has a great likelyhood of having a bad internal seal and within a short time if you keep driving it a rebuild will be necessary no matter what the current cause.

With your mileage you are due or maybe overdue a trans overhaul.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician