There are couple of good videos on YouTube about this install. Make sure you use prescribed diameter hole saw. Tape working surface and cut it around with new sharp utility blade. Put transducer dry an tighten the nut. Tape the transducer and area around the hole and cut around transducer rim. Remove it and bed it in 42/5200. I did not used rubber washer. Make the nut snug but do not over tighten. Prep is 90% of the time.