There are a number of things that can be done to seal the lead screw opening in the control box. That was a big topic years ago! The easiest one is to slide a garden hose washer on to the lead screw, a better version uses a thin, larger diameter, plastic washer between 2 garden hose washers. A more elaborate seal uses a short length of PVC pipe bored to a close fit over the lead screw & glued to a piece of sheet plastic that's screwed onto the control box housing.
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Roy
