Whenever I have run into a need for replacement parts, I have always tried abroad starting with the original manufacturer. I usually write to them and if the model is out of production, they usually write back with references of their authorized service centers who could help. If the company itself is defunct, I usually search for service centers of that product who usually help. Finding parts in India is not possible unless salvaged. Its always good to use OEM spares. However hunting for spares, equipment, etc is a journey and one cannot use the 'go-to-portal-and-buy' approach.
Another good habit to develop (and I have learnt this the hard way) is not to wait for equipment to fail and then look for service centers. It is very important that one actually researches this aspect just after or even before purchasing gear. If you enjoy a piece of gear, a beak down can cause heartbreak and frustration so why take a chance. So even when your gear is running well, not a bad idea to check online for key parts that can fail, and identify sources where you can get OEM versions of them. I used this approach with my Nakamichi deck and when one morning, the drive gear collapsed, I knew exactly where to go for a OEM replacement.
After driving down hi-fi boulevard for a long long time, I have figured out that its worth spending the extra buck on OEM parts and New Old Stock equipment. For those who live abroad, there is no comparison to having one's gear serviced at a professional service center. To start with I suggest you don't loose heart, use disruptive methods for searching and be patient