Nishijin Late '75 B type sumo pachinko

[Spyder138]

If you do as Jeff suggests you should see the balls roll away from the seesaw. If they don't then there is an obstruction and you should get a good idea of where it is. A chopstick is a great tool for poking around and freeing up stuck balls. If everything seems to move OK check to see if you have a jam after the seesaw. If you don't have enough balls in the hopper and upper track the jackpot won't trigger and can cause winning balls to back up. Once there are enough balls in front of the jackpot mechanism to provide proper payouts the ball jam after the seesaw should clear. A photo of that area may help.