I have changed the colour toner cartridges but the machine won't recognise the cyan has been replaced. I have tried turning off the machine, taking all cartridges out then back in etc. I'm not sure what to do next...

should, try cleaning the heads of the one that don't pump ink with achol and swab

I knew it needed to be reset to recognize the new toner. Glad you found the info in the electronic menu. Thanks for using Fixya. If my suggestion was helpful could you please rate it for Fixya. Thanks

Just because they are new toners, doesn't mean they can't be faulty.

Faults that show in just a single colour are almost always related to THAT colour toner cartridge.

TRY THIS

If you still have your old cyan toner, swap the chip from your new toner and put the old toner in the printer, then test.

If the lines are gone, it's the NEW cyan toner cartridge.

Cyan cartridge is OK, means that the display shows the level of toner in the cartridge, right? Then chip it is ok.
Try another cyan toner, the printer may be that it has broken the opening flap of the laser. Or check if the laser's flap cyan is blocked.

printer working ok-did 50 colour photos ,6x4 when i made a mistake and pushed the print button when there was still about 1 inch of the previous photo still being printed.This print emerged with overprint of about 1".Thereafter the printer has refused to operate properly the next print being heavily discoloured.It then told me to replace the light magenta cartridge-this I did and the discolouration changed hew.It then told me to change the magenta and light cyan carts.-I did and discolouration changed again.It then told me to change the yellow and cyan=siscolouration now bright
red over coloured. I then successfully printed a letter in B&W proving that the black cartridge was still working.However as soon as I tried again to print a coloured photo it now tells me that the machine does not recognise the black cartridge and orders me to change it and until I do refuses to take any instructions telling me to install the black cartridge cprrectly.The black cartridge installed isout half full and has successfully printed copies and photos.I have carried out the suggested remedies by the machine and none were effectuve.How do it the infernal machine working again???

5 flashes says the printhead is not installed properly, you may need a new printhead,

Remove Cyan Cartridge. Trun Off the Machine.
Now Insert Cartridge, make it properly inserted.
Trun On the Machine And The Error Is Gone......
Try It

It is the developer. All colours should be changed at the same time. This can be accessed via the right hand side of the machine, when you remove the cover. (where the output tray is)

Your machine has got a toner pump on each of the colours wich transport the toner through pipes , these pipes get blocked and needs to be vacuumed out to clear the blockage .i got the service manuals if you need any further assistance

I had the same problem and found that one of the toner cartridges must have not been seated properly. I removed the black toner cartridge and re-fitted it. The printer now works fine again with no errors. 17H is a code relating to a fault in the rotation ......... possibly one or more toner cartridges need checking. Use the menu on the printer to turn it to the appropriate position (i.e. engine menu then select replacement of whichever toner you are checking).
Hope this fixes your as well.
Chris