Check your media switch on the bed. Look inside the machine you will notice a toggle switch or an orange triangle on the right hand side.
Tell me, when you press LOAD, physically watch the platen and tell me what happens when it reaches the switch. Does it ride over it and keep going? If so, it will be contaminated with dirt and will require a clean.
Early versions of the K3 had a toggle switch, the later versions had a clear or orange load switch.