How to clean a Sears water distiller?

It says to not use soap. I have 'crud' inside it already. Have been using it daily...on my off days, I used it like 3 or 4 times, to get my water supply up. Now, that it is there, when I wipe it out, the 'crud' is not removing.

Do I need a cleaner that Sears recommends? Or is there a better way?

Thanks in advance.

Have a Awe-filled week forward!

Peace,
Beth