Hi sir:
You must understand , that each in any field of Industry; like Contactor, Relais, Solenoid, they generated some Heat normal, by the electromagnetism induced in the magnet.
However you must test with your finger, if the coil is Normal or Abnormal heat, compare with other Impression coil in the same machine, and see if they are Heated too much, in that case , can be a faulty mechanical-electrical, and will be a good idea to replace.
Blessing