Hey urgent. Truck won’t go into reverse
 

My 48re just quit going in reverse and before that I did notice that my shifts were very slow / took longer to go into next gear . What could cause this. I’ve heard it could be my servo or I need to adjust my shift linkage but I trust y’all better 😂 Please help ASAP. Need truck working by Monday. Also when this did happen I noticed that the selector that has PRND21 had a blue square around all then at one point then when I put it in R the box blinked for a lil . Any help appreciate thanks