Here is a picture of mine.
When the light is running, there is a voltage drop across the emitter of 3.6V. This emitter, or an equivalent is easy to come by and they are not very expensive. Try this link.
https://www.fasttech.com/products/1609/10001584/1116600 Warm White
https://www.fasttech.com/products/1609/10001584/1116601 Cool White
I would buy one of each for 2 reasons. I might not be successful soldering the first one and I might like the color of the second one better anyway. Less that $3 total buys both.
EDIT:
I just reread your first post. You said there is 18V across the PCB. There should only be about 3.6V. That means the driver is blown and that 18V across the LED blew that also. You need more than just an emitter. On second thought, it could still be just a blown emitter. I suppose that driver could still be OK. Because the emitter is blown (open circuit) you could be reading 18V open circuit. Perhaps with a working emitter in place, the driver will limit it to 3.6V 0:)
I will go one step further and check out my driver.
A picture of the driver.
The MT7201 is an LED driver, it can handle an input of 7-40V and drive an LED at up to 1A. Probably 750ma in you case. Here is the spec sheet for that driver. No one expects you to build another driver, I am providing it so that someone else here with more knowledge of these things can suggest a replacement for you.