There's a lot of troubles the unit. its probably cold soldered, capacitors needed to replaced, defective power supply and regulator. if you see plenty of moist of capacitor in the surrounding it means you have to replace it, enlarging case or melting tag. some capacitor their feet get rust seem all part were getting worn out. try to soldered the feet of the component maybe there were ring o circle on the lead. There were some cases in physical appearance when you staring on the lead its okay but in the inside where not. i usually was to re-solder stage by stage. then look if improvement on your work. ask me again if nothing happened.