I had a similar problem last year when squirrels ate some of my organically produced hose which ran from the tank to the pump inlet. I guess green products can be pretty tasty.
Unlike some installs mentioned here, I had a separate barbed hose tap low on the side of the FW tank close to the drain hose. Dropping the chloroplast involved removing the many self tapping screws and it came right down. There was a 1 inch layer of Fiberglas insulation which also dropped down. The FW tank was accessible for repair.
I spliced in some new hose and was able to replace the partially eaten barbed hose tap at the tank. I also tightened up the drain hose assembly while I was down there.
I bought new self tapping screws and fender washers for the reinstall because the old ones were pretty rusty and some had broke. I had some help from the DW getting everything back up in place. I used the original holes except for the screws that had broken.
