Definitely a nice reel. Congratulations on the freebee!
My suggestion would be to fish with it for the rest of the season and then send it back to Shimano in California for maintenance. They will strip it down, relube and replace all worn parts.
Unless you are very experienced with working on these reels, I would suggest that you leave all the maintenance to them. If you want to just open it up to add lube or anything, don't take the main gear out. If you take it out and don't put it back
exactly the same way, the gears may not feel as smooth when you reassemble it.
Good luck with your new toy!
-Bob