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Nice try but it didn't get far.
Can not see something marked serial number but I take it that must be the string of digits that isn't identified. Tried putting in the Model Number (21B07M) and the Product Id and what i took to be the Serial Number, and "CM0700" into the search box. Philips claims no knowledge of any.
I wonder if they make a conscious decision to ignore their CRT monitors. Even searching for "monitor" didn't help. Came up with loads of stuff, lots unrelated to screens, but where it did come up with a PC monitor it was numerous newer models.
Maybe I'll Google for some dodgy driver websites tonight and see if that comes up with anything.