Yes that tank is the flush water tank fed from the locker outside.The pump is below and you should see the flush tube coming from the pump to the side of the toilet pan inline with the flush tube jet.
Check the pipe hasn't come off one or other end.
Go to page 17 [page list top line question list.
select the second section and open the following question THETFORD PORTA POTTI BENCH TYPE WILL NOT FLUSH look at my answer for email address send email I'll send instructions for repair/replace of puimp.
I I will underatand f you don't wish to reveal your email address so wait and I will copy instructions into the forum.
Reason for this is forum no longer will let emails be added to replies. Me and the wife are in Seaton Devon in my caravan on Manor Farm site [Visiting Daughter and family in town will be home late tomorrow and will email or add instructions on wednesday. it's not a hard job easy peasy. I've just had the same prob for second time on my caravan C2.
Bob Worthing West Sussex
Bob
April 2009
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