HP Laserjet 4250 error 60.02 are caused by the lifter motor not properly lifting the tray 2 cassette. 

This can be caused either by a faulty tray 2 cassette or a faulty lifter motor. 

Pulling the tray 2 cassette out and inspecting it will reveal any problems. 

If the tray is free of any defects a replacement of the lifter motor should resolve the error 60.02 your Hp Laserjet 4250 is experiencing