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I don't think that being cleaned caused the problem, unless the cleaning was done with the wrong solvents or some similar inappropriate methodology.
It sounds to me as if simple aging has produced a serious defect in tone generation, whether it is by 'chips' or an integrated circuit, or by other means. Your Hammond will require a good repair specialist to look at it and determine the cause. If you will tell me your local zip code or town/city and state, I will look up listings and give you contact information for the nearest Hammon specialists to your location.