3rd row seat stuck in position

Hi all, i’ve got a 14 plate qashaqai +2 and recently the right hand side boot seat has become stuck about 90% into the upright seated position. It’s upright enough to be useable but not fully there if that makes sense. Whatever I do to the pull cord to try and lower or raise the seat it does nothing, it seems as if there’s a spring in the pull mechanism that’s missing or broken somehow as there’s no movement in it at all. Even when pushing and pulling the seat itself with a bit of force it’s just locked in position and can’t be moved. Before I start stripping it down blindly is there a quick fix or anyone with a similar issue previously able to offer any advice? Thanks in advance.