I just bought a 1992 Harley FXSTC Softail Custom. It's got the two tanks connected by crossover links at the top and bottom of the tanks. I can only get one tank to fill with gas. Once there, the gas doesn't seem to travel through the crossover links to level off with the other tank. I have complete removed both tanks to check them and the crossover lines for blockages and debris. They are all clean. Lastly, there are screw on caps on both tanks. Only one can be removed because the racheting cap is backwards to the threads in the tank. Please help me with any suggestions for how to resolve the half full issue?