This is a common problem; I had it myself. The cause appears to be that too much lube was added during manufacture and it shorts out the contacts. All you need to do is to squirt some contact cleaner - making sure it's the stuff that leaves no residue and contains no oil - into the slot around the dial and rotate it a few times. That's it, simple and cheap as that. I did it to mine about a year ago and it's worked perfectly ever since. I see you're in India so probably won't have a Maplin near you, but this is the one I used for reference.
PCB Cleaner : Electronics Cleaners : Maplin Electronics. Great stuff to have anyway as it'll remove all kinds of crud from most things. Smells like dry cleaning fluid so is best used outdoors I'd imagine.