Your tractor was made by Murray and private labelled for Scotts. Murray went bankrupt and Briggs & Stratton picked up the bones at a bankruptcy auction. B&S won't be of any help, as they have orphaned old legacy Murray. The 46572X8 uses a Peerless (Tecumseh) VST-205-023B hydrostatic transmission. According to Peerless, transmission is non serviceable, and oil can only be added or changed with a tear-down. It uses a synthetic oil in the hydro portion and 90W EP gear oil in the differential section.

The hydro oil is maintained behind a bellows, which keeps air out of the system. Tecumseh does sell a bellows and oil kit to replace the hydro oil. To service, you need to remove the transaxle, and place it on a bench, bellows side up. You will need almost 2 quarts of oil. The service kit is 799030, containing the bellows and 2 quarts of oil, which lists for $50 and can be had on internet from $40 to $45. This may or may not address our problem.

The only bullet proof fix is to replace the transaxle. Tecumseh/Peerless part number for the VST-205-023B is 799031 and list price is $725. Can be found on internet for as low as $599.

Good luck.

Here is a link that might be useful: 46572X8 Parts List