You'll need to determine if the meter itself is physically bad or the circuit driving it.
If you've got any sense of adventure, the first step would be to remove the cover and make sure a connection hasn't come loose.
Beyond that, you'll need test equipment, experience with electronics and probably a service manual.
If you're not capable, don't know anyone who is and don't have the funds for a service visit, you're probably stuck. At that point just be happy the unit plays and it's just a visual effect that's broken.
If you've got any sense of adventure, the first step would be to remove the cover and make sure a connection hasn't come loose.
Beyond that, you'll need test equipment, experience with electronics and probably a service manual.
If you're not capable, don't know anyone who is and don't have the funds for a service visit, you're probably stuck. At that point just be happy the unit plays and it's just a visual effect that's broken.