If it's a thetford say so using the answer page to your question I have some self compiled help info on the C2 bench type thetford cassette toilet.
Or you could go to the thetford website if you'd rather but they don't show info on their pdf page on non flushing toilet to safe you the problem of finding the free download pdf follow this below.
UK & EUROPE www.thetford-europe.com
Australia www.thetford.com.au (Even get request from Australian campers)
Australia site has stockist list.
HOME PAGE SELECT ENGLISH {if in Australia forget this selection)
NEXT PAGE SELECT CUSTOMER SERVICE (top line)
NEXT PAGE SELECT USER INFORMATION (left of pic) also 'Ask thetford' is on this page.
NEXT PAGE SELECT REPAIR INSTRUCTIONS (left of pic)
NEXT PAGE SELECT BUILT IN TOILETS [top right of pic]
NEXT PAGE SELECT This is where you select your toilet range. Search alll if unsure of type/range
NEXT PAGE PDF Files You should be in the pdf folder list on your Thetford toilet. Start downloading.
To direct link to the Thetford download site type in the following
www.thetford.eu/web/show/id=51498/langid=42
Don't bother for Thetford fridges they tell you for safety reason to take it to a service centre
Bob
April 2010