If the ink tank is not properly installed, it interferes with the operation of the print head.
See the following images to get an idea of proper print head position.
[ When the ink tanks are not properly installed ]
The ink tank is not set firmly.
The ink lamp is not turned ON.
[ When the ink tanks are properly installed ]
The ink lamps are turned ON.
attention:
Always remember "Do not touch the Print Head Holder while it is moving."
Wait until the Print Head Holder automatically stops.
Do not even attempt to stop/move the Print Head Holder by holding it.