The filter pump in those tanks is a standard 200 LPH circulation pump, which sits in the bottom of the filter box.
1.) Unplug old pump
2.) Remove the bottom plastic plate from the filter box
3.) Pull the old pump downwards. It just sits with its outlet pipe in a little hole, pumping water upwards
4.) Replace with new pump in the same orientation. If pump does not fit, please see below.
5.) Push bottom plate back on
6.) Plug pump in (do not run those pumps out of water to avoid damage)
Depending on available model and replacement pump, the supplied circulation pump might not fit into the filter compartment. In that case you can simply remove the outer casing of the pump, see pictures below.