Cassette service door replacement

Hi all struggling with our 2003 symbol and have been trying to fit a new door, the issue is I can't seem to remove the old one once I removed all the screws

Anybody else done this project please advise

Mark

In the end I just replaced the door and had to leave the original frame in situ 

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tidy! as long as the old frame is watertight should be fine.

Thanks it seems a good fit and the rubber gasket fits well