fuel gauge resistor

[fun in dirt]

Trying to get my fuel gauge working this weekend. It's not the wire from tank, ground wire , or sending unit. We dropped the tank & checked all that out. Read on another thread a while back about resistor on back of the gauge being a problem sometimes. What should the resistance be on it? And is the resistor on the back of the temp gauge the same thing (because I have one of those if it'll work)?
Another thing, I'm not to confident in the printed circuit sheet on the back of the whole cluster; why can't I just wire the fuel gauge up direct?