If you have got the cluster out it might be worth replacing all the bulbs...as mentioned below:-
If you are noticing dark areas of our instruments at night, likely you have one of the backlight bulbs burned out. To replace these bulbs, unfortunately, the instruments must be removed from the vehicle first. The standard bulb which comes stock with the unit is an incandescent or filament-based light bulb, as shown above. The life expectancy of these bulbs is estimated at about 2,500 hours, thus replacement of these bulbs during our repair procedure is highly recommended. Our replacement bulbs are higher quality
than the originals, named "Long Life"; they can expect to provide about 10,000 hours of service.
A welcome to the forum too.
Splitpin