Hi Chris, you have on of the very early HEX-NETs. A little more than 2 years ago, we redesigned the nose and we changed the plastic material from which it is molded to make it less brittle as it aged. I know the early HEX-NETs went out with our original design. From the picture and from our records, I'm near certain yours was an original design. I can tell by the locking tab - another area we changed.
As Mike has said, it will not hurt use to not have the tab. Replacing the nose on one of these is not for the faint of heart. I would not recommend trying it. But if you want to try, we could send you a nose assembly. Understand, if you break the HEX-NET main board in the process, there is no warranty on that.