3 part fix;
1. Make sure the scoop is still curved correctly
2. Use some sticky backed rubber in the back of the scoop to deaden the ball when it hits it(available at any hardware) normally comes in soft, medium and hard density. I found medium the best but its cheap as so experiment with which suits best(brand dependent I guess)
3. Lower the saucer by about 1>2mm by removing the screws under the playfield and using some small washers as spacers.
Do this and your problem WILL be fixed, I hardly ever get bounce outs now