My flintstones had a ball stuck in the green Dino on the ramp, I found once just having a look around the play field,I've got two lost balls in a flinstones. They both went in towards the crane and never came out. (Same thing on two separate occasions)
Playfield has been up and down, shook the crap out of the machine, it's even been on a roadtrip up and down the country to someone else's house and they still haven't appeared!