If the display function does not work, replace the meter unit.

Check 3-6: Neutral Indicator Light (LED) Inspection
Meter Unit Circuit (ZX1000J Model)Shift Fork Guide Pin/Drum Groove Wear Inspection
Measure the diameter of each shift fork guide pin [A], and
measure the width [B] of each shift drum groove.
If the guide pin on any shift fork is less than the service
limit, the fork must be replaced.
Shift Fork Guide Pin Diameter
Standard: 6.9 7.0 mm (0.272
0.276 in.)
Service Limit: ...
Engine Sprocket Removal
Remove:
Engine Sprocket Cover Bolts [A]
Engine Sprocket Cover [B]
Flatten out the bended washer [A].
Remove the engine sprocket nut [B] and washer.
NOTE
When loosening the engine sprocket nut, hold the rear
brake on.
Raise the rear wheel off the ground with the stand. ...
Air Cleaner Housing Assembly
Install the ducts to the air cleaner housing.
Fit the projections [A] of the duct into the slits [B] on the
air cleaner housing.
Tighten the screws [A].
Torque - Air Cleaner Housing Duct Screws: 1.1 N·m (0.11
kgf·m, 10 in·lb)
Install:
Air Cleaner Gasket [A]
Duct [B] ...