Hello, the reasons for this issue with the machine are as follows:
1. The adjustment screw on the bill feeding tray is loose. Adjust the middle screw on the bill feeding tray clockwise until it feels resistant and cannot be turned further.
2. Check if there is any foreign object stuck under the bill wheel. Open the top cover and remove any foreign objects under the bill wheel.
3. If neither of the above two points is the problem, the machine requires repair.