I have an old transistor radio with three or four wires disconnected on the circuit board and headphone jack. I know the radio works because I held the wires onto the terminals and listened for a connection. Anyway, a couple of the connections are on the circuit board, the other two are on the headphone jack. Would it be difficult to just solder them on myself? Are there any particular precautions I need to take? I have a very old "hotshot" soldering gun, the tip got hot, but not enough to melt the solder on the board. Thanks