You can make an attempt to free the printhead by doing the following;
1. With the power off, open the top cover.
2. Turn the power on and as the unit attempts to perform the initial test cycle, gently pull on the carriage assembly to see if it will move to the left. If you get no response. Turn the power off.
3. Now, turn the power on and gentley push on the carriage assembly to the right in an attempt to take the pressure of the of carriage and free the jam.
If neither of these work, then you are left with no other choice than to take the printer apart and get at the locking mechanism and free the carriage so it can move away fromt he purge unit and help you to locate the probable jam in the purge unit.
Canon PIXMA MP800 Error 6A00
