Tivoli uses a non standard tuner so do not use any sprays or cleaners on it as these can damage the part beyond repair. As Paul suggests, excercising the tuner is the best first step. Basically with the radio on or off and at no volume turn the knob/dial fully clockwise then counter clockwise a number of times. This will help scrap off oxidation which seems to be the issue with noisy tuning.
If you get noise/crackles when turning the volume knob then this part only can be sprayed with a cleaner such as Deoxit.
If noise problems only exist when you turn the selector switch then yes that could be a problem and may need to be repaired (cleaned) or replaced.