I am trying to save the life of a Seiko quartz. I think the coil is dead but the board looks ok. I have tried cleaning it with some bicarbonate of soda mixed into a paste. It has helped but there are still signs of the greenish stuff left over. I don't want to be too aggressive in case I damage the circuit. Should I just give it another treatment until it is all gone or does anyone have another method I could try.