Slipping trans?

Or "direct drum" is the one with the input shaft on it.
The order of removal would be pump, front drum, and then the direct drum.
Pull the pump, remove the second gear band, then lift both drums out by the shaft.
There are instructional video's on the internet.

Which is the REAR drum of the 2 drums ,and trans will have to come out to fix it.

As someone said check the fluid first , then make sure the throttle valve linkage , (KICKDOWN) is set up properly.