Small Engines (Lawn Mowers, etc.): Ariens Hydro, hydro drive, ariens

Question
I have an Ariens YT12, model #935020, serial # is unknown. The problem I'm having is it's moving slower and slower. The only thing that has worked a little bit, is someone suggested moving the shifter lever back and forth from forward to reverse. It does help but it's temporary. Not sure how to check the fluid level in it. I think it's the marks on the dipstick on the cap, but I can't read what it says. Also haven't been able to find what kind of oil goes in there. Belts are new and seem to be tight. Any help will be greatly appreciated. Thanks

Answer
Lance
You may to try and purge the tractor hydro drive by going back and forth in a short distance
Three quarts I would think should more than cover it. Allow an inch below the top of the case. Zip it forward and backwards in push mode to purge out air as needed
From my Experience getting air out of them is 'nearly impossible' and that getting old fluid out and replacing with proper fluid will also be 'nearly impossible' Not so much encouragement there....The other thing you might try is googling the Hydro Gear model number and see what you come up with. The oil you need if you can get the old oil out is 20W50 Try and adjusting some of the linkage.