I have owned two 1992 245s over the years, of one of which I had to replace the sender unit.

My experiences are that if the pump clicks off, the meter will show full, or if it was clicking off really early no more than a needle's width below full. I kept the original float ball just in case.

There is indeed only one way to put the sender unit in, so misaligntment seems impossible. The sock rubs against the bottom of the tank, so its alignment could be checked by looking for the marks it left over the years.



This is the pic I took of the inside of my tank, it still looked this squeaky clean after 25 years of use.

I was trying to imagine how the sock could interfere with the float, but looking at Art's pic, I'd say it's possible if it were rotated by about 45 degrees, especially if it's the original black sock that is not as flat as the white one in this photo.



Writing down fill volume from half a tank (accorrding to the meter) won't tell you that much. The meter doesn't seem to be completely linear, dropping more slowly in the top half of the meter scale and faster in the bottom half.