I have a issuse that am trying to get as much to know before I dig into the work.  My 3 spd OD which is a top loader in my 55 Ford seem to want to drop out of 2nd gear and go to natural at time.  So before I tear into it need as much insight as I can get to what to look at or for.  I know that under the cover there's a spring with a small ball bearing. Does someone know what this does?  Inside there are shifts that are grooved for the ball to slide into as the forks move to different positions.  Would this be a area that might cause the dropping out of 2nd gear issuse? 
I kind of working of what left of my memory when I was much younger.  Back then I would just rip into it but now at my age i would like to know what to look for, as those old task have become much harder to deal with.
You all have seem to have great input on other issuse I ask about for that I say great job and great people.  HELP