Modifying anything can make the situation worse. Rebuilding or restoring back to original is the best solution.
The teeth of the ring gear and drive gear may not be in perfect initial alignment as the starter is engaged (neither are synchronized with each other). In the picture I see a slight taper and rounding for the drive gear. If the drive gear is also spring loaded, it should move into mesh when the teeth are aligned as the starter motor just begins to move. The original design would be to make the meshing happen as quickly as possible creating less wear. If the teeth meshing does not happen quickly, the torque motor will spin-up to maximum speed (whine sound) and the unmeshed drive gear will be spinning too fast to engage.
If the foot start linkage is worn, it could cause the motor to start before teeth meshing. Not good.
