Quoted from FlippyD:
Welcome to the club!
Now about your problem. Incline is the easiest and quickest fix, should be at least 6.5 degrees. Could also be that your playfield, rubbers, and balls are too dirty. I used to have balls get stuck their occasionally but since the last time I shopped the pin and changed the balls it hasn't happened.
Also, how lively are your pop bumpers? If they don't kick the ball around much it might not get enough inertia to travel down the playfield.
Thanks! Pop bumpers are extremely strong. But I will follow your advice and wax the area.
I also needed to ask about the center drop targets. I need to replace one drop target (worn out) How do I remove the board? Just remove the C-clips? Thanks!