The sprayer nozzle inside the live well should screw off, just the head and you should have threaded pipe left. Once you do that you can open the valve and use an air compressor to blow backwards thru the system. Just short burst should free up anything. I used a small rag to seal the air compressor nozzle when I blew backwards thru the system.

You will also have mid way access to the front live well hoses thru the drain in the floor between the drivers and passengers sides. Not sure what you mean by "does not work at all" with the front live well but you can always use a hose to the fill the live well and see if water drains out the back. Mine were cut just under that drain in the floor. I took a coupler and another piece of hose to run it on to the back. If the pump does not work up front make sure and check you have power to the place they plug in once you get the batteries out. It is a white 2 prong connector. The wire color are listed inside the fuse block cover just in front of the motor controls at the driver seat. Mine were good old green water hose also. They may have used that at the factory back then. It is as durable as anything else you can use and I went right back to it. I bought a short good quality garden hose and all has been fine.

I built a new battery tray for mine. I used pressure treated plywood and coated it with the automotive undercoating stuff you can get at the autoparts store. Sand it a little so it gets good adhesion. for the straps I used the nylon straps that are about 18" and loops on both ends. Then used bungees to secure the batteries. I stapled them in place under the battery tray when I built it. It is not "hi tech" but it works well, was cheap and easy to replace. I put a little extra piece of plywood on the home made tray to hold the batteries in place on the long sides and the strap secures then in the middle. If you measure the tray so it fits tight you will not have to do anything but lay it in the bottom and it should not move. I also moved the batteries as far forward as I could back there and it actually seemed to help it get on plane a little better. The middle piece of the battery tray that has nothing on it is a separate piece so I don't have to remove the entire tray to work on anything.

The front hook is accessible by taking the faceplate where the trolling motor plugs in up front along with the front light switch and tilt/trim for the motor. it could be the bolts are loose on the back of the eye or the entire plate is loose but I hope for your sake it is the bolts. My plate was loose and I re-secured it again with fiberglass resin but it has come loose again. Not sure what my next plan is there.

My 373 had one "lounge" seat where your has two. I took that out and decked the front in all the way back to the consoles. You end up with a lot more fishing deck and a lot more storage.