I am rebuilding a lathe and have run into a broken bolt with a missing part. The missing part is a wedge just under the top of the apron on the left side. Appears to be an adjustment. I have not run into this before. I can determine the width but the length and thickness are a mystery. I am assuming the bolt went through to a nut in a slot in the wedge but I am guessing here. Can anyone enlighten me on this mystery wedge.