Yes, the seal is serviceable. Either visit the dealer or pop the seal out and visit a bearing house.

Thanks for your help. I believe the seal has to be removed from the inside, but I am not positive.

Well, if all else fails--you can always pack some new grass around it!
All kidding aside, i'd think a new seal would be available. you should write down all model numbers, etc. and contact a place that sells bearings and related stuff. Maybe, the old seal has some numbers on the metal parts.

These boxes are quite dependable all in all. I've only had a few apart and they were older than yours. Should be an external seal I would think. Deere parts does show seals as serviceable. Don't know exactly what deck you have tho.Might have to clean it up a bit and give an inspection. Paint makes it all look the same.

***"Paint makes it all look the same."***
Yeah, and grass & grease really finish the camouflage.