How much is the Class Imbalance Problem rates?
There is no general rule but you better to use such techniques (SMOTE, sampling etc) and try to obtain 50:50 if you can. 
You can utilize my another answer (just ignore multiclass part).

My suggestion is you should create more samples by synthetic data generators like SMOTE. You have a model with very less observations (197). The model may not fit well thus data generation may help your for that case.

Hope it helps!