I've just invested in the cheapest, (but not nasty) holding tank there is, and installed a portable toilet. I finally gave up trying to salvage the electric toilet and holding tank I went through nightmares installing years ago, when the bright sparks who govern our state brought in restrictive legislation re raw sewage discharge, but failed to bring in concurrent legislation requiring the marinas to put in the pump-out facility. As a result, virtually no marinas here have that, and to get to a legal spot to discharge was a 5 hour trip for those of us with displacement boats, so of course you can deduce the outcome.
Finally my system, because we tried to use it as little as possible, seized up. Both pump motors and hoses - somewhere - I could not find it, and I was not going to strip it all out and replace it, only to still effectively have to operate illegally. So...once I finally came to the conclusion even if I got it all working again we would still not be able to be legal, two weekends ago I removed said loo, blanked off all hoses, closed the seacocks, fashioned a new toilet plinth cover to hide the hose connection holes, and I have installed a portable camping type toilet. Problem solved, now legal, no possible plumbing blockages and macerator pump seize-ups. Happy boater again.
But that was probably not what was in your mind...but maybe it should be..?