Ran transmission dry briefly, still works but fifth gear is now singing?

Ran transmission dry briefly. still works but 5th gear is now singing... want to replace damaged internal parts. What do you believe is damaged in there? People speculate I burned the synchro- I am confident (mostly) to open the transmission and replace anything ruined but can't find where to buy such stuff. As I am here, I believe I have a parasitic battery drain. At the same time, the driver's side window switch went from one tap automatic roll down to a need to hold the button down to get it down. Thank you for being here, I heard good things about this site. Thank you, Matt