The WTCPL uses the same soldering pencil as the WTCPT, which I inherited some time ago, and Weller (now part of Cooper) still makes new replacement parts and tips for these old workhorses, which I think is fantastic.
Anyway, you'll find the datasheet for your model here, including troubleshooting guide, assembly diagram and parts list:
Weller Tech Sheet - WTCPL Series
In my case the magnetic switch was still working (there's instructions on how to test each part) but the heater barrel was open. I replaced the barrel and the nut (the newer barrels are slightly larger in diameter, so you might as well get a barrel nut at the same time) and the iron works perfectly.
You can get these parts from Digikey:
EC234-ND - HEATER ASSY FOR A TC201T IRON
BA60-ND - ASSY BARREL NUT FOR PES51&50
SW60-ND - SWITCH ASSM FOR SOLD PENCIL (magnetic heater switch)
Some are listed as zero quantity, but they order them and I got mine in about 2 weeks. Other replacement parts are available, but if you have to replace too much (or the more expensive parts) on the iron you might as well buy a new iron. When mine broke, I fixed it and purchased a new one that was adjustable for $100. Now my old one is the backup, and I don't mind bringing it to electronics group meetings.
However, this is a worthwhile iron to fix if the cost is not too great. The new fancier models have more features, but you really can't beat how durable and usable these old wellers are. While you're at it, you might as well get another tip or two.
Not affiliated with digikey, but they are a reasonable online supplier if you are in North America
What’s the proper soldering iron temperature for standard .031" 60/40 solder?
There is no proper soldering iron temperature just for a given type of solder - the iron temperature should be set for both the component and the solder.
When soldering surface mount components, a small tip and 600F (315C) should be sufficient to quickly solder the joint well without overheating the component.
When soldering through hole components, 700F (370C) is useful to pump more heat into the wire and plated hole to solder it quickly.
A negative capacitor lead to a heatsinking solid pour ground plane is going to need a big fat tip at a much higher temperature.
However, I don't micromanage my soldering temperature, and simply keep mine at 700F (370C). I'll change the tips according to what I'm soldering, and the tip size really ends up determining how much heat gets into the joint in a given period of contact.
I think you'll find that very few soldering jobs will really require you to change your tip temperature.
Keep in mind that the ideal situation is that the soldering iron heats up the joint enough that the joint melts the solder - not the iron. So the iron is expected to be hotter than the melting point of the solder so that the entire joint comes up to the melting point of the solder quickly.
The more quickly you bring the joint temperature up and solder it, the less time the soldering iron is on the joint, and thus the less heat gets transferred to the component. It's not a big deal for many passive or small components, but it turns out that overall a higher tip temperature results in faster soldering and less likely damage to the component being soldered.
So if you do use higher tip temperatures, don't leave them on components any longer than necessary. Apply the iron, apply the solder, and remove both - it should take just a second or maybe two for surface mount, and 1-3 seconds for a through hole part.
Please note that I'm talking about prototyping, hobbyist, and one-off projects. If you are planning on doing final assembly with the iron, repair work for critical projects, etc, then you'll need to consider what you're doing more carefully than this general rule of thumb.
Best Answer
The difference in the structure of MOSFETs and BJT is that the former have a thin insulation layer. I don't know if this is easier damaged than the rest of the crystal when heating it. But I would most strongly advise you to get a temperature controlled soldering station. If you leave your iron unused for a minute the temperature will rise to levels components won't like.
Also, most likely a temp controlled station will have proper earthing which is even more important than temperature when soldering MOSFETs.