What's loose, the connectors or the plug itself? You can crimp connectors to tighten them, and some wraps of black tape can resize a connector that's too small. I've had a few close ones where the connector is the wrong shape, but a bit of trimming with an x-acto blade was all it took.
Another option if you ain't worried about pretty is a couple of barrel connectors of appropriate gauge.
PS - great rig. The QR series are the KING of I/O. I ran an entire house off one for years. Also have that great Sui tone ...
Oh. And if it doesn't work when you plug it in, make sure the PRE OUT/AMP IN jumpers are there. If not, use short RCAs or some stripped romex wire.