Yeah these boards definitely need a good cleaning! Canned air didn't quite cut it.

Hi and thank you! I personally work at 350 C / 662 F with my setup. This seems to be a good point for vintage PCBs and fairly robust through-hole components like this when using leaded solder. For smaller boards that are more sensitive you may want to start lower around 300 C and if you find 300-350 isn't hot enough to efficiently heat the joint then you could go up to 400 C / 750 F. That's about the top of the range I would go. Any further and it gets too hot and oxidizes the tip rapidly. The one exception would be soldering chassis grounds when you're dealing with the surface area of the chassis in which case a bigger tip/higher wattage is necessary. Also, on heat sensitive components like LEDs and diodes, I'd use forceps or an alligator clip to absorb some of the extra heat. There are several factors here to consider that affect heat transfer from your iron to the workpiece. Including the surface area you're heating, the surface area of the tip, the condition of those surfaces, the iron wattage, the temp of the iron, melting point of the solder, and amount of flux used. I used 63/37 rosin core solder wire in 0.031" diameter with a 60W microprocessor controlled iron. By tinning the pad and the iron and using the broad side of the conical tip, I was able to get perfectly adequate heat transfer.

@@SRASolderLab Great answer - thanks!