ChrisNeilan wroteInteresting. I had that same problem. It would not fit into my 520 fence. I have two 520 table systems so I tried it in the other fence. Fit was perfect! Left me scratching my head!
Really? The t-nut doesn't fit in the t-slot.
One fence is different than the other...maybe.
Old fence or new? Does a straight edge reveal anything?
Pictures, guys. Pictures.