Bitsetter Probe Button came out

During a job I noticed the probe on the bitsetter was suddenly missing when it went to measure a tool. I was able to find the probe and put it back into the bitsetter but it bottoms out and stays depressed.

I opened the bitsetter and discovered that there is a threaded washer that had come off the end of the probe. I replaced the washer but the probe just slides up and down in the bitsetter, I assume there is a spring that is missing to hold tension on the bitsetter,

Has anyone else had this happen?

See the diagrams at:

If you have difficulties putting things together post a photo here.