Small Engines (Lawn Mowers, etc.): John deere sabre hydrostat problems, hydrostat, transaxle

Question
A guy offered to give me for free a 2000 John deere sabre tractor with a 42" cut.  He says the transmission (hydro) works for a while and then slips or quits working.  Surely this shouldn't be shot already.  Is there and adjustment or anything that he's missing?

Answer
 Hello Dale:

 Add 1/2qt of SAE30 Engine Oil to the Transaxle and See if this Corrects the Problem. Make Sure the Transaxle is Dirt Free(Clean). The Transaxle Must Stay as Cool as Possible. Check the Belt for Stretch after Operation. Hope this Helps. I am Here if you Require more Assistance. Let me know what Happens, Please. Thanks.

 Good Luck

 Respectfully

 John