91 nissan terrano wont start

First things first; 1) check Terminals and make sure tight & clean 2) Make sure the batteries good 3) Make sure connection from battery to starter is secured 4) Make sure its not the starter clicking if it is change it. 5) Make sure starter relay is good located with all fuses!

Just had this happen on my 1996 Terrano, same motor.
You will need short 14mm and 16mm ringspanners due to lack of space (cheap ones tend to be short) remove the battery cable (10mm) undo the 14mm nut to remove the cable from the starter solenoid, squeeze to unlock and unplug the small wire to the solenoid, undo the two 16mm bolts which hold the starter motor one from above, one from underneath, I also had to remove 3 12mm bolts from the inlet manifold which hold the bracket of electrical connectors, to get the starter motor up past the connectors.
At the cable end of the starter motor, ther are two screws which hold the brush plate to the end cap, if you unscrew these and they just snap off because they have carborized from arcing then you have the same fault. Remove the two long screws which hold the starter motor together, remove the end cover you will likely see there has been arcing between the brush plate and the end cover, clean this up with sand paper or similar. Two brushes are connected to earth through this connection - no earth = no turnover!
I turned the heads off the long screws and threaded (5mm x 12mm long) where the heads were, then screwed the short threads into the starter motor, screwing a nut down onto each of the long thread ends to go under the brush plate, then refit the brush plate winding the nuts down until the brushes are fully on the commutator, then the end plate, and two more nuts on the outside, so when tightened, ti holds the motor together, but also clamps the brush plate to the end cover, and reassemble.

My autobox will not change up to final gear in the box and some times itdoes