How much does it cost to service a transmission? It has 146,000 miles. on 2006 Chevrolet Malibu

The tranny is starting to shift hard and slip.

Asked by for the 2006 Chevrolet Malibu
the service is about 119. be aware that it may not help your issue. it sounds internal and may have to be overhauled.

Would changing the fluid and replacing the filter help? It has never been serviced since I had the car.
services like oil change are always good, but usually too late to fix an issue. by all means, give it a try but it may or may not help.