Diagnosing is a bit more difficult than that. For one, the relay on the machine affects power being passed to, through and from the coin mech. Additionally, the settings on the unit affect the overall behavior of the coin mech operation. I would start with posting a pic or listing the state of the switch and price DIP switches behind the sensor plate. The two ears sticking forward on the top corners can be pressed and the coin head will tilt away.
TRC-6800 Install/Config Guide
https://www.dropbox.com/s/xgtoze4c41temyu/Mech-TRC6800H.pdf?dl=0