Hi sir:
Thank you by his reply .
After check his model, please see this
1) control system, defective , check if the LED is ON, otherwise, defective PCB, repair or replace it.
2) reheat the PCB, for dry + colder joint solder !!!!
3) test the +24Vdc regulated power supply in tolerance 0.7% up or down otherwise replace it !! + bridge rectifier after power transformer , can be defective
4) look, for loose wires, and corrosion connector!!!