Our College has a Graupner Mz-24 radio, which has developed some issues with range. It does not have range of even 200 meters.
I want to get it checked and repaired, but i don't think there is a service center in India.
Where should I get it checked/repaired?

Try RCB. They sell Graupner Radios

We have tried that, they told they don't repair, contact graupner service center.
And those service centers are located in germany, UK, USA, etc. but not in India

Contact SJ Propo, Korea. They now own Graupner

Any damage to the antenna. Post photographs of the antenna end.