Mission 765 Problems

I have a pair of Mission 765's that I love. However, they have started to give me problems recently. Sometimes my sound partially cuts out in one speaker. I had them connected to one terminal and the plates connected both terminals together. I thought that might be culprit, since sometimes I could push on a plate in between terminals and the sound would magically come back in full. So I removed the plates, and I ran two sets of wires to each speaker, with one wire connected to each terminal.

The problem seemed to have went away, except now it has been doing it again. I noticed that when I push a speaker terminal in, it will stop, then continue based on my pressure. I took the crossover in one speaker out, and tightened the terminal nuts on the back side. That seems to have helped one speaker, but now my other speaker is doing it.

How should I go about repairing this? I am capable of using a soldering gun, heatsink and minor repairs. However, I don't know where to look for what parts might be bad, what connection might be old, etc. Where do I begin troubleshooting my speakers?

Thanks for any and all help!