Why my clock radio is running fast?
I'll make a guess or two. Old clock radios from the 1990s often used mains frequency for the clock reference. Many also had a battery backup that would use an RC circuit that might have 1% accuracy during a power failure. Also biplexed displays operating from center-tapped transformers, but that's not so important.
One possibility is that there is something creating spikes on your mains that are getting through whatever filtering they had in there. Either the spikes are new (maybe you added an appliance) or the filter has deteriorated for some reason.
Another possibility is that the mains clock has entirely failed and it is running on the backup clock source. Unlikely if the clock/radio has no place for a battery.
Another possibility is that the power supply filter capacitor has dried out and you are getting so much ripple on the supply that the clock cannot operate properly. Just look for the biggest electrolytic cap and replace it.