Your pgbk nozzles are working. I appears that the residual cleaner on the purge pad supplies a small amount of fluid to the nozzles. It could be either the pgbk channel in the printhead is bllocked (blow air through the black inlet port and see if it comes out/bubbles out the black nozzles), or the purge syslem for pigment black is not functioning.
The potential causes for a non-functioning purge unit range from blockage in the vacuuming system ( which requires a lot of patience to unblock, or considerable disassembly to clean), to a disconnected hose in the system (again, requiring disassembly to re-connect). I have had solid blockages in purge systems that required using fine wires as tools to dislodge the blockage in fine passageways in purge pump manifolds. I have had tubes come loose INSIDE the vacuum pump, and also tubes come loose connecting the purge pad to the vacuum pump.
The vacuum pump used by Canon is a peristaltic-type pump.
Test the purge system for operation.
1. Apply cleaning fluid to the purge pads with an eyedropper with the print head in the cartidge change position. You must be able to build up a standing pool of fluid on the pads that stays. If the fluid disappears from the purge pad over a minute or two, that indicates a leak in the purge system that must be found and corrected.
2. If the standing pool of fluid persists as expected, then close the printer cover and let the printer go through a cleaning cycle. Re-open the printer and visually inspect the parking pad. ALL TRACES of standing fluid should have disappeared. If not, then the purge system is not functioning (most likely clogged).
3. Inspect the black rubber gasket around the parking pad(s) for distortion. This gasket seals against the print head nozzle plate so vacuum can be established. If it is distorted, the ceramic insert may have been disturbed. Typically there are at least four rubber "tabs" that lap over the ceramic pad that must be positioned correctly to the gasket has the correct shape. The gasket can be "nudged" with a fine wooden tool if needed.
Wayne
