Canon Pixma IX6770 / IX6870 Printer Repairs - Purge Unit Replace. Printer ink suction Part is Printer Purge Unite. when purge unite is not functioning correctly ink is not correctly flow through the print head. We are using a CISS fixed Canon IX6770 printer. Stay tuned, we will show how to fix CISS to Canon IX6770 / IX6870 Printer soon.