Congrats, finally!
Now show us some pics of MB as well

I think the problem is the plunger may have gotten moved out of the center of the shooter lane. If the plunger rubber is not at the center of the ball it can cause the ball to go flying off the sides, or if it is lower than the center of the ball it can/will cause the ball to propel upwards. I have had a couple instances where someone was rough with the shooter knob and shifted the shooter out of position a little.
There are a couple screws and bolts that hold the shooter to the cabinet. Loosen those and shift the shooter housing into the proper position and re-tighten firmly.

I replaced the black shooter tip rubber with a white one which just happens to be a little longer and that helped quite a bit.