Is it possible to over tighten your clutch cable and break the...gasket? for lack of a better word, that is at the firewall?

As I look at the cable as it goes through the firewall (into the car), the seal/boot is 2 pieces. from the picture on IPD's website (granted, not a good one), it looks more like it's one piece.

There is also some give in the cable at the firewall, like I can pull it about an inch (at most).


The issue that lead up to this is that after I finished replacing the clutch (and put it all back together), I tightened the cable and set it at what i thought was the correct specs (about 1-3 mm of play in the cable at the fork). But when I go to turn on the car and run in through the gears (w/foot on the clutch), it obviously isn't set up right. Even after I loosen it a TON and then re-tighten it, it shows the same symptom.

What would the symptoms of a broken/loose cable at the firewall be?