As a first timer here, I thank you for your replies. The enquiry was on behalf of a friend who has a 1503c with a cracked screen, so replacement is his only option.
I'll follow up the links that have been posted, there may be a solution to be found...
For myself I've one point five 1503 with crts in them (one only half works and will be kept as spares if I can't resurrect it - it's been 'modified' shall we say...
Old technology never dies, the repairs just get newer