panasonic DMR-ES30V dvd recorder?

regarding changing 1204 & 1209 capacitors. 1209 has positive and negative wires and the negative is marked -, however 1204 is different altogether, it is not marked at all and has a plastic cap. I found the recommended replacements at RS components but the 1000mf 1204 is marked pos + neg same as 1209, so I presume 1202 can go either way round. The socket for 1209 is also marked, the other is not. Maybe someone who has done this mod can help