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These SW electric focus motors have been around for quite a while, and I
have heard no complaints about them, other than the early ones chewed
up batteries in no time , even when switched off, necessitating fitting an
on/off switch to break the circuit. They are very strong, and will turn
the focuser wheels and shaft even if you forget to unlock the focuser
after an imaging run.[assuming that a Crayford style focuser is being used, not a rack and pinion].
Assuming that you are using the Crayford style focuser, when you say it strains and struggles, does the motor actually stall, or keep turning, but not move the draw tube? As I said, the motor is strong, so loosening the tension on the shaft will just cause it to slip. If the motor keeps turning but the draw tube doesn't move I suspect that the tension needs increasing not
decreasing. When the tension is right it should be quite hard to move the
focuser in or out by hand by pushing or pulling on it. It's a pity that the
electric system doesn't have a quick release so that large focus adjustments can be done manually. I just push or pull on my focuser to
do large adjustments.
raymo
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