The loco was produced between 1955 and 1960. The distortion suggests you have an early example with plastic safety valves from 1955 or 1956 and it is not repairable. Later examples had bodies made of a different material with brass safety valves. Replacement replica lights are available from James Day of The Train Collectors Society. A total of just 16000 of these models was produced during the period so it is a relatively rare Triang model and in top condition boxed collectors will pay very good money!
Happy modelling
Gary
Happy modelling
Gary