Help With Convoy BD06

A new Convoy BD06 had a problem with the driver. I received a new driver.
The BD06 has a side switch.
I did not open the bezel to get at the LED.
I just removed the retaining ring of the driver.
When I removed the driver, a small black plastic ring with a split in it came out along with a spring.
I am assuming it is from the side switch….that I removed the driver in the wrong manner.
I glued the black plastic ring back together.
However, I don’t know how to get it back together.
Any help would be appreciated.
Thanks