Had a talk with a Canon engineer today that I know....he says that from what you describe it is unlikely to be a full ink absorber foam, but you can remove it carefully from its housing (without having to remove anything else) and give it a wash with soap and warm water, let it dry and then carefully slide it back correct side upwards.
If the problem remains then it is a documented problem where the ink leaks before the absorber becomes full, a problem which has resulted in the issue of a Canon Service Bulletin along with a modification.
To have an engineer do this costs around £100+ apparently, but I have managed to obtain a copy of this
confidential bulletin

as you may be able to negotiate with Canon customer service as it would appear to me to be an inherrent defect and hence the 1 year Canon warranty is irrelevant and the repair should be done under your rights under the Sales of Goods Act.
Allen-uk...........I will remove the attachment once you have got it
Edit: Attachment removed.