Toro Zero Turn Rider 74366 Lawn Mower Tractor Rider Ztr "gearbox stop leak" Questions

...you can get under the tractor to look up and check it out. Is it possible to add gear oil to the gearbox? Mine was leaking for a while and now has stopped....I worry its got NO

...either side. no oil leaks no damage anywhere it has not been overworked with this little yard. the gearbox is not even dirty. this is very disappointing. on such a new machine could this be a defect ...