How to fill hydrostatic transmission fluid on Poulan Pro

SOURCE: How do I check fluid level on YTH150 Hydrostatic Transaxle?

My Husqvarna hyrdrostatic transmission is sealed, and yours may very well be also. That means no changing the fluid.

SOURCE: MTD PRO RIDING MOWER/LAWN TRACTOR 18 HP ENGINE HYDROSTATIC DRIVE

In the back of the mower...probably under the seat, there should be a lever to release the transmission, or it is on the back plate. As far as the noise when trying to move drive the mower, the brake in the back, next to the transmission is jammed, use a 1/2 inch wrench to loosen it maybe 1/4 turn and this should unlock the brakes

SOURCE: transmission fluid low, hydrostatic transmission

Quoted from your Owners Manual. . . . .

TRANSAXLE PUMP FLUID
The transaxle was sealed at the factory and fluid maintenance is not required for the life of the transaxle. Should the transaxle ever leak or require servicing, contact your nearest authorized service center/department.

SOURCE: How do I check hydrostatic

first you need to know who made it and the model. there are only 2-3 companies making all of them.
look for a stamping on the bottom along the axle, if not there you are going to have to drop it out of the mower and find the info on top. possibly you could lift the seat up and see the top of the tranny to get this info.

once you have the maker and model of the tranny, find their website and download the service instructions. many of these are made with lubrication for life. meaning they can't be topped up or changed, if the fluid is low or bad you replace the whole thing.