Craignovak

Just replaced the fuel level sending unit in my 2007 C280 4matic (it was leaking when the tank was full). Completed the process and now the fuel gage only reads 1/2 full with a complete fill up. Thinking one of the two floats (on fuel level sending unit and the one on the fuel pump side) is sticking or possibly rubbing on side of tank? The fuel level gage worked correctly before this replacement. Not sure where to start (which side) to start with. Not sure which float actually controls the fuel gage? The fuel level sending unit(behind drivers seat) or the fuel pump (behind passenger seat). Any help would be appreciated. Thank-You