Thanks to one and all - I would look inside, but I'm loathe to do anything that might allow the seller to absolve himself of responsibility by allowing him to say that I have caused the problem by meddling.
'He' is a volume seller with a great feedback reputation so I've messaged him and asked him for a response, assuming that he won't want any overt negative comments about a potentially, trivial problem. Its annoying because I had work I wanted to do with it today, but I'll let you know what the outcome is.
Once again, many thanks.
Al.