Print Quality Issue - Brother MFC-J6530DW

I have a Brother Business Smart Series MFC-J6530DW printer which until recently has been printing fine. However now, with the Print Quality set to 'Normal' which is the setting I generally use for my day to day printing, my documents are illegible. The quality of printing is appalling. The only way to produce legible documents is to set the Print Quality to 'Best'. The printer is just out of its manufacturers warranty period.

I have run the printer through its head cleaning process several...

Print Quality Issue - Brother MFC-J6530DW