If the SU's are in good shape, I see no reason why they shouldn't work properly as a replacement for the Strombergs. Apparently, there is a problem with the SU's you have installed. Maybe if you describe in more detail what problems you are having we can better help you as to a proper course of action and maybe pinpoint what to do with the SU's that you have. Also, what car are these on and what type of SUs are they??