It's probably 1107, so Nov 2007.
There will be a groove worn in the large retaining "washer" on the front of the vise, and/or the matching groove in the spindle. If you have a lathe make a thicker replacement - I had to do that on my C3 to remove slop. You can buy thicker replacements too, but it's possible they might be too thick - depending on the wear in your spindle groove - in which case you're going to be doing a bit of filing on it.
definitely a Q