Question about Sun Mar composting toilet - dry, self-contained

[Mari_55]

My composting toilet has worked great for about six months. However, when I turned it today, the contents had become liquid and had moved throughout the outside of the drum. I don't know how to fix this. Should I just empty everything and wash it down with vinegar? Is this a sign that there is a problem with the separation of liquid and solid? I know this sounds gross, but it is my first time using a compost toilet and I am out of my depth here.

[MountainDon]

Is/was the bottom of the unit, under the composting and under the drum that catches and drains excess liquid full?  Is there a drain tube installed? Is it plugged?

I placed a half inch shim under the front edge of ours to promote good draining.