<VV> gas gauge reading past full

[Ray Lough]

I am sure this question has been asked and answered in the past but can 
somebody explain what would cause the gas gauge to read over full all the 
time on my 1969?  I installed both a new tank and sending unit in 
May.  Everything worked fine until a couple of weeks ago when the gauge 
went past full and stayed there.  I check both the ground and hot lead to 
the sending unit and both have good connections. Is there a specific 
problem that would cause this over full reading?