Maybe this will help. I just saw it posted to garden web forums:
"When this topic came up yesterday I decided to find out how hard it really is to change the transaxle fluid on the GT 5000. For anybody interested this is what I did.
I had bought a set of Hydro Gear service video from Ebay that demonstrated tearing down and rebuilding the transaxle so I felt confident an oil change would be straightforward. On may way home I stopped at Walmart and picked up 4 quarts of 15w-50 Mobil 1, Hydro Gear ships them filled with conventional 20w50 oil.
I drove the tractor around the yard for five minutes to warm up the oil as the video recommended. I then brought the tractor into the garage, removed the wheel weights and loosened the lug bolts. Then I lifted the back end with a floor jack under the hitch plate and removed booth rear wheels. Remember to block the front wheels since they do not have breaks. I released the idler puller arm that keeps the drive belt in tension and worked the belt up and off of the transaxle. All the control links are on the right side of the tractor, near a hole in the frame allowing good access. I pulled the cotter pin holding the parking brake linkage, removed the washer and freed the linkage from the transaxle. Then I set the parking break to pull the bar out of the way.
The motion control lever linkage is attached by bolt with a lock nut. Those came off quickly. The next item to go is a bracket on the lower front center attaching the transaxle to the tractor frame. Remove the three bolts and pull the bracket free. The only things left are four bolts, two on each side, holding the axle to the frame. I removed those and pulled the transaxle as far to the left as possible, this allowed me to slide the left side of the transaxle free from the frame and rest the hub on the floor while I freed the right side. The free wheel engaging rod is attached to the transaxle with a spring and can be left on, just make sure it doesn’t catch on the rear draw plate as you remove the transaxle. This was my first time removing the transaxle and it took me about 25 minutes. But now that I know what I’m doing I see it could be done in less then 10 minutes.
Before going further I cleaned the transaxle off, it’s surprising how much mud and other stuff gets caught on the top. The cleaning took about 15 minutes to do a through job. Then following the videotape instructions I removed the breather tube from the top and inverted the transaxle over an oil catch pan. I left it drain for 20 minutes, came back and removed the plug covering the oil top off port found on the upper right rear of the axle housing. I left it for another 15 minutes before moving the transaxle to the bench and examining the oil. These was some milkiness, which I took as water contamination along with slight smell of carbon. I measured the oil and found it was slightly more than 3 quarts.
I then started to add oil through the breather hole on the top. The oil level reached the bottom of the oil top off port at about 3 ¼ quarts. I put the plug in and added another ¼ quart to compensate for trapped air. I reattached the breather tube and reinstalled the transaxle in the tractor. I didn’t time it, but I think it took 15 minutes to get it back together. I then started the tractor and purged the transaxle.
All together it took about 1 and a half hours to do. Since the oil was not in perfect shape, and was low I think it was worth doing and make it a part of my 200 hour service. Keeping in mind I put more than 200 hours on the machine the first year I’ve owned it, and worked it very hard to boot, I think for many people there would be no need to perform this oil change in the first 10 years they own the tractor. There is an internal oil filter that I left alone. To change it the transaxle’s bottom cover plate must be removed, and a seal kit (which I did not have) is required to reseal the unit. The procedure I described will probably work for Craftsman lawn tractor too, but I don’t know."
