I'm trying to replace the din 5 with a din 8 for the rgb mod. Your probably right about using a hotter iron, I've just been reluctant to use one in case I lift a trace or pad.
I was hoping it could be the sucker, a new solder sucker is cheaper than a new iron
I did the job with a 25 watt iron - I wouldn't go any more than that, as you risk pulling the tracks off the PCB.
Use solder flux, a good de-solder pump, nice clean iron tip, also I think I used a solder mop:
Which is similar to the braided wire like you get in the screening of co-axial wires (i.e. audio and video). It just absorbs the excess solder - just like a mop with water I suppose!
Be very patient, and get the bulk of the solder out. Then use a flat head screwdriver or similar tools to move the legs of the DIN clear of the PCB tracks. Working one by one, you should be able to free up the DIN and get it out.
BTW - keep the DIN, you may find that you need to cannibalise a few bits of it, to make a good 8 PIN DIN, since they seem to have slight differences between manufacturers.