Glad everything came out well. Bob Caldwell is correct, using a chemical that biodegrades waste may help to liquefy things, but not all chemicals are created equal, do some research and find one that has enzymes, and is not just and odor controller. Some chemicals can actually cause the waste to harden on the bottom of the tank.
For the gray tanks I have started using a cup of liquid Cascade dishwashing soap added every other full tank or so. Within weeks of using our new Silverback the tank sensors stop working correctly. After one treatment while moving from one park to another and letting this mixture slush around with a 1/4 tank of water, the sensors are working good. The tank sensor cleaner that can be purchased at CW did not do a thing. I have also started to add some liquid fabric softener to each tank to lube the valves and tank walls to prevent build up. I can not take credit for this I found this method on another post, but I can say it works.