HP printer (Milton PO4)

This is an HP OfficeJet Pro 8600 printer. It's been a brilliant office printer but now has a 'paper jam' message on the screen, which I am unable to clear, despite following the instructions to do so. Therefore I think it may have developed a fault. Other than that it's been very well looked after and looks in almost new condition. There is quite a lot of ink in the printer currently and full black and magenta spare cartridges as well.