Is your model the first version, meaning how long have you had it?
The older ones had some least desired retracts with end switches that get dirty and hence you get what you are experiencing.
I would recommend to call HORIZON TECHNICAL and tell them exactly what you posted here and hopefully they will send you the newer retracts, assuming your model is one of the first batch produced.
I can go into what needs to be done but, I am not certain you level of modeling or skill level with retracts / electronics.