Hurrah, at last I've found the correct connector for the IOP/measurement port. JST SH1.25 6 pin. Only took me 3 goes... https://www.ebay.co.uk/itm/5-PAIRS-6-PIN-Micro-JST-SH1-25-Connector-Plug-Socket-1-25mm-150mm-Cable-/272781618226?hash=item3f830d2c32