THE COIL
There is always a small spark between the vibrator contacts of a coil, and in time the platinum will be burned and corroded, the oxide that forms being an insulator and preventing the flow of the current. In such a case the points may be smoothed with a fine flat file and polished on a strip of leather, or if too far gone for this, may be renewed by soldering a short length of platinum wire to the adjusting screw and a plate of the same metal to the blade. While this job is a delicate one, it is not beyond the range of a careful amateur.
When the insulation of the coil or condenser breaks down, as may result from overwork or long use, it should be returned to the maker, for the construction of a coil is exceedingly delicate, and repairs on it require expert workmanship. It is not advisable to take the coil apart in any way, beyond the vibrator parts, for inexperienced handling may injure it beyond repair.