Printing apparatus and methods of operating a printing apparatus

A method of operating a printing apparatus including operating a rotary drive device to move a printhead configured to print onto a substrate that is moveable in a substrate path adjacent the printhead, wherein the printing apparatus includes a linkage coupling the rotary drive device to the printhead to cause resultant movement of the printhead, the linkage including a first part that is configured to convert rotary motion of the rotary drive device to linear resultant movement of the printhead along a first axis, and a second part that is configured to cause angular resultant motion of the printhead, the method including monitoring a force in the second part of the linkage during a monitoring period, using a monitoring device, to obtain monitored force data, and using the monitored force data to determine a parameter of at least one of the printhead and/or a substrate support against which the printhead is arranged to bear during a printing operation.