I have the same Marcum and used to have the Vex. It took me a bit of an adjustment to figure out the gain etc. Once you get used to it all will be fine. I actually have my Marcum in getting fixed now and back to the old Vex. I noticed that it IS easier to see the bottom and jigs etc, but the Marcum shows better separation, so with the Marcum I see two separate lines for two fish, the Vex would show one bigger mark – hence easier to see, but not as accurate. Same is true with the bottom, I see more stuff on the bottom with my Marcum, but a better solid line with the Vex – details I guess.
I get what you’re saying, im just wondering what its going to be like fishing in 20-30ft of water if I have to have the gain up this high in 9ft.
The “TC” was the True Color upgrade. Initially when the LX3 first came out it was only 2 colors. The TC upgrade (and all the newer units) have 3 colors green, yellow/orange and red.
I would guess its the transducer if you are using a verified good new battery and its fully charged. If you turn the unit on you should hear it clicking quite loud and be able to actually feel it in your hand if you place it in your hand.
The battery tested at 12.5volts when we got home yesterday. The transducer does click very loud when out of the water.