I should have said that after I had cleaned out the bottom of the pump mine did run intermittently but was getting less and less reliable as to when it "felt" like working - not very convenient (sorry another awful pun)
You WILL need to drain the flush tank as the pump and its fittings and electrical connections are under water when the tank is full.
You could always drain the pink liquid into a bucket or other suitable container and refill the tank with same when you have finished. Help to offset the exhorbitant cost of the pump.