How do I change hydro-gear trans oil?

[Craftsman Garage]

I have a Craftsman PYT 9000 model no 247.289800 that I think from my research has a hydro-gear trans on it, and when I’m driving (except for frat area once it gets some speed) it will make these low pitched whining like sounds, it’s when I first press on the pedal and when going on a even slight incline. Assuming it needs a fluid change. Not really sure how to do it as I have never really done maintenance on one of these transaxles. My question is how do I change the fluid in it, is that what you think is the problem, and do you think something else could be wrong with it?

 

[Craftsman Garage]

UPDATE: This is a hydro gear 618-0319 transaxle

 

[Rivets]

This service manual contains your model number. https://www.hydro-gear.com/wp-content/uploads/2021/09/BLN-51260_P8.pdf

 

[Tiger Small Engine]

This service manual contains your model number. https://www.hydro-gear.com/wp-content/uploads/2021/09/BLN-51260_P8.pdf

Probably no access port except breather tube on top. Will need an extractor to get out most of oil. Often can only get out about half, give or take, because of design internally. Refill with 20W-50 synthetic oil. Only buys you time, and filter is not cleaned/replaced as a result. Once finished, make sure you purge system for any air trapped.