hey mpg9999,
here are a few tips i've heard to keep from having the 5th gear popout problem. first, don't lean on the shifter knob.
i hear a lot of the popouts are due to bent shift forks, not broken ones. bent ones only bend due to constant pressure, i.e. leaning on it.
the other thing that could be causing pressure on the forks are bad mounts. replace any mount that looks worn...or hell, if you have the funds, replace all of em. most notably, the front insulator i think.
other than that, i think that covers some stuff....good luck
-Chris