Replace it with a Fishfinder
Last winter, I mounted an Eagle 160 fishfinder in the cockpit bulkhead where my old SR instruments depthfinder was. I sent the transom mount transducer back to Eagle and they exchanged it for a puck mount (for trolling motors) transducer at no charge. I took out the thru hole SR instruments depth transducer and drilled out the guts, then carefully ground the new puck transducer to fit in. Epoxied it in the old SR carcuss, and put back in the hull. It works like a charm, plus gives me some entertainment with fish on the screen, plus battery voltage, etc. all for $129 from Boaters World. Plus it came with a coupon for a speed/ temp transducer. I did the same with it, and it worked until I put it in the hull, so on that one I must have ground to much, but that one would have been the bonus anyway.