Thetford toilet and the water leaks down pretty quickly. I am thinking it’s the blade seal and I guess that means removing the toilet to do the job. If thats the case, I am tempted to pay someon...
I have two toilets and both have been holding water fine for the past 14 years.
I keep water in the bowl all the time which keeps the seal from drying out.
I also clean them with Dawn dish soap at the end of every trip by pouring the dish soap in the bowl and then using a three inch toilet brush to clean off the seals.
Have you been keeping water in the bowl constantly or did it dry out?