You Need To Touch On Components If……..
After fixing an electronics project kitset i found that it would not turn on. Double check on the board for dry joints, broken tracks, solder bridged, wrongly installed components and all seems to be in right order. Even the ICs on the socket had been replaced and yet no sign of improvement. One method that i have not use yet was touching on the components. When i apply some force on the components with my finger i found that one of the transistors was lightly shaken. Upon careful inspection again with a x 10 magnify glass there were actually 2 of the transistor pins broken. It was just a mild break on each pin/leg. Before i join back the track and the pins i had a look at the connection again with my bare eyes-guess what ? both pins looks so perfect on the joins and you did not even realize that actually it has a slight break.
The moral of the story here to tell you that after you have exhausted trying to solve an intermittent/solid problem in circuit board and still could not find the fault then try the above method. Be careful that you have fully discharge any high voltage in the capacitor and no ac main voltage in the board.