How do I fix a leaking toilet pan in a toilet cistern with no ball ****?
Is it leaking near the cistine and the pan? These can be quite difficult to stop even when new. It’s a matter of getting a watertight seal on both the pan and the cistern, not helped by the plastic nut. Repositioning can help or an additional ring seal on cistern fitting can add a bit more pressure to seal the two. Tighten evenly. You can also try using silicone sealant squeezed into the plastic threads before you tighten up. This material will stop up any tiny gaps but won’t prevent you unscrewing it again later if you have to take it apart.