Thanks to everyone who helped out with my starter solenoid arcing question- that's now a work in progress. So in addition to that, the exhaust leak, the diesel leak and various other fluid leaks the back door won't lock. This is the first time I have ever bought a vehicle on eBay without seeing it first- lesson learned! 
I have removed and cleaned the lock and it works perfectly, with the key as well but only when the door is open. Try and lock it when closed and it just won't do it. It looks like the door isn't closing far enough to engage the lock but it can't go any further- even with me pulling on it and with my foot on the frame.
Anyone got any ideas? Currently a security risk as she's out on the street but I do have a massive chain and bike padlock round the pedals and through the sterring wheel!
I have removed and cleaned the lock and it works perfectly, with the key as well but only when the door is open. Try and lock it when closed and it just won't do it. It looks like the door isn't closing far enough to engage the lock but it can't go any further- even with me pulling on it and with my foot on the frame.
Anyone got any ideas? Currently a security risk as she's out on the street but I do have a massive chain and bike padlock round the pedals and through the sterring wheel!