My sp10 had a similar issue, and I only happened across it because of another members review. My led was not sitting flat. When I inspected it, it was raised to one side with a horrible cold solder connection. It worked, but once I heated it and tapped the oz 
of solder out from under it, it was much brighter.
And to slijim, 25w might not be enough to unsolder the wires on the mpcb. 100w would certainly do it, but a large tip might cause problems. As far as reflowing, I use my wife’s electric griddle. though she doesn’t know that.
My SP 10 b emitter fell off completely. It would operate dimly at first then not at all. Here is an excellent video on how to reflow an emitter for the noob like myself.
That iron will get hot enough to reflow it will just take a couple mins. I normally use a cigarette lighter. And have the mcpcb clipped into something. Takes like 10 seconds to reflow. I use a Weller 40watt iron and the lighter is still my favorite way. You can use a hot plate as well just need to get your solder or solder paste to melting temp. And the led kinda sucks it’s self and centers on the mcpcb. I use tweezers to push any excess solder out
Thank you! I pressed down on the LED of my glowing Sofirn and it lit up to full power. Guess I need to learn how to reflow emitters.