Night of the Living Numpty - Part I

[Ted Maul]

Ok so having a great evening, but fed up so going to hold myself up to ridicule here.... twice
Part I. Been out of the scene for a long time and now have my 1st brushless motor and speedo, yay - SP GT2 and SP 6.5 pro.

Cannot for life of me solder the 5 wires to the speedo, eitehr the black/red power or the three motor wires. Motor connections fine, but *******d if I can do the speedo end. Iron is very old, like 20 years old I used at Uni for pcb work, marking faded but think it says 25w which sounds a bit feeble, is this the problem? Heatsink gets plenty warm enough...

Is there a trick to this or am I just rubbish at soldering