This is a general information note regarding the electronics that control printers and other devices.
This fault is known as a Dry Joint and can cause a wide range of faults and errors.
I have come across this problem many times in my years servicing printers and appliances.
Shown below are before and after pictures of a power supply from a Kyocera FS-1010 that has suffered a couple of dry joints on the main power plug connector.
After re-soldering (I had to sand the connectors clean to get the solder to fuse correctly).