Can someone please instruct me on how to service (not remove/rebuild) a vintage 1946 three speed manual transmission? I have never done this before and need to find out how one checks the lubricating fluid, where the access points are for servicing etc. I don't have a clue at all of what I'm looking at. I think the unit is OK by the way it works, but until I mess around with it I really won't be able to tell just what condition it truely is in. I really don't want to pull it if I don't have to. Seems to function alright, just sounds a bit noisey but that could be the nature of the beast. Any helpful tips to guide me through this will be greatly appreciated.