Have error code 1007 on my MG5420. Have followed roller cleaning instructions, have removed paper tray numerous times, have checked paper guides, have shut down printer, no help. I have only printed 8.5x11 and have not changed any settings.
The 1007 error is an error caused when there is no paper in the upper tray.
You stated that you are printing on letter sized paper. Letter sized paper can only be loaded in the lower cassette.
This error is caused by the paper source in the printer driver being set incorrectly. Before printing, please make sure that you have letter sized paper and lower cassette selected in the printer driver.
If you are still experiencing difficulties, please reply to this post with the version of Windows that is installed on your computer. If you are using a Mac, please let us know what version of OSX is installed.