the Approximatly yield of 55,000 letter size impressions at 6% area coverage for the toner cartridge of th wc5875
im not sure how it did only 700 ,however check if the toner cartdridge physically still have toner inside it or not ?
if yes and the machine telling you to replace the cartdridge so it could be there is an issue with the ATC sensor on the developer module OR it might be that you replace the cartdridge before the machine asking for it .
also make sure about the toner mode on the driver and select th toner saver mode to reduce the toner consuming
