Why do you think the slightly thicker fluid kept any fluid from flowing. Seems unlikely, but you should know. Are you sure that the forward/reverse switch was in forward when you tried the fluid? Mine came with the switch on reverse and there was no fluid although I could hear the pump running. Then I experimented with the switch and realized it controlled the direction of the pump.
Please excuse me if the fluid was thicker and really is the cause. Just seems a bit touchy if it's true.
