I may have assumed the key became loose again a bit too soon.
After inspection it is still tight, but I think the pin moved out slightly causing friction.
The jaw still moves about 1/8 inch in either direction which is annoying.
I may flip the key over and see if that helps any.
Thought about loctite and may do that once I have finished testing.
Drilling new holes is not going to happen. I may drill slightly bigger holes though if needed.
LAFSTER: you were mentioning this over on the vise repair 101 thread so if you fix it and have time can you make another post over there saying how you fixed it.
i'm guessing when you are mentioning 1/8 (1/4 inch on the other thread) of slop that is maybe side to side? I thought it was in and out which is also common on some of these that have been used quite a bit.
from side to side sounds like you need to make a wider key? in and out maybe a thicker horseshoe washer or some have used welds to narrow the worn gap in the hub where the horseshoe maybe rubbed off 1/8 inch of material from use.