There is a new technical download site which allows access to Canon technical bulletins for free directly from the site. Of course you can still search from so many different manuals for purchase but all bulletins are and will always be free! It’s a new site so manuals are still being added. You can even find HP, Samsung and Ricoh service manuals there so bookmark the page and keep checking for the latest manuals.
It’s worth taking a look at the Technical Download Centre.