More than likely your escalator is jammed. The escalator is the device that is screwed to the top horizontal window of the machine and carries coins across the window.
Take the back door and bonnet off the machine. Looking at it from the rear, there should be two vertical arms screwed on each side of the wooden case that are in the down position, holding the mechanism in place. Grab a hold of each one and rotate it up.
Gently pull on the handle and you will note it pulls something on the mechanism that in turn, pulls something on the escalator. Make note of the part on the escalator it pulls on.
Place some paper on the floor or a table. Slide the slot mechanism out of the machine and set it in the paper. Reach up and apply pressure (pull down) on the part on the escalator we discussed. That should cause coins to move across the escalator and free up the jam. If they do not, look closer at the escalator. There are little bars with teeth on them that separate the coins. They are held in place with springs. Pull them back and use a screw driver to separate the coin jam. Do this as necessary until the coins are evenly spaced between the teeth and you can clear the jam in the escalator.
When done, put the mechanism back in the case and be sure to lower the two holding bars in the side to keep mech in place. Test with coins to make sure it is working befors putting the bonnet and back door in place.