I also went through a couple of senders and had the 3/4 indication problem. When I finally compared the new one to the original more closely I found that the swing arm travel was more on the new one (about a 3/4" or so). I had the correct resistance readings at both ends of the travel which threw me off. With the longer swing it was hitting the top of the tank before the end of the swing travel. A slight bend in the arm was all that was needed to correct it. Now it reads full on the gauge with a full tank of gas.

Good Luck

Jim