To all of those who have the gift of being able to troubleshoot and fix most anything: My father-in-law has a Home Depot John Deere L130 with hydrostatic drive. As of today, hills that it would climb ... it no long does climb. Loud noise (humming, pumping, almost a grinding) can be heard. Looking through the owner's manual it says that it is a sealed unit and should be serviced. Looking through the internet, sounds like it might be low on oil. Can anyone tell me what could be going on and how to fix? If it HAS to go into the shop, any WAGS (not SWAGS) on what it might cost to fix it?