Bad Cornwall IV?

You call that an upgrade?

Good to hear you solved the issue.

Just goes to demonstrate that good physical connections are just as important as everything else.

The bywire is Fake not true biwire from the Xover ,from the 5-6 pair I have rebuilt ,and connectors are lower quality gold over brass, when all quality connectors are copper,gold  far better conductivity. I have  rebuilt many Klipsch speakers the Xover parts are not even average quality ,the jumpers are NG . Get the tweeter replaced 

and then seriously consider rebuilding the internal Xover  which is a Major upgrade in sonics , crites type are ok at best you want Top quality resistors like Path audio ,

and a quality brand name capacitor.

In 2022 all the money nerds are trying anyway possible to maximize profit margins even if it means a degrade in performance. It’s always been that way to an extent but the engineers had more power in earlier years. I don’t know about the Cornwalls but speakers that cost multiples of a thousand dollars should be using at least mid grade audiophile components. Would probably only add 50 bucks to the speaker unless going crazy. I don’t wanna buy something for 5-10k and need to worry about upgrading it. Ridiculous! Rant over..

Those slate colored things, on the outside of the binding posts, are called "jumpers" they allow you to use a single speaker wire to feed your speaker. When you remove the jumpers, you can use two speaker wires (bi-wire) which people say sounds better.

Note: the binding posts, at least on my Forte 4s, do not allow extreme tightening with spade terminals. You must use banana plugs or your contact is compromised.

Glad to hear you solved your problem!