As for all the things on this world, never say never.
One day this medium power rotator decided to not turn on the left anymore.
This page will describe howto open , understand, repair that thing and show its inside life.
Openening the rotor is simple,there is only 1 red cable to be
disconnected and resoldered in the open position
for the on-table tests.
A lock-washer keeps the rotating gear on the shaft,
pull it with care,and take it off the shaft. 
Complete motor unit
The bug of this project,seems to me,laying between the rotating tongues
and the rotor limit friction spring 
Rotating gear with limit tongues, when the rotor comes to one end it is quite probably that the friction spring SLIPs out of the tongue
so the rotor cannot rotate backwards anymore.
This fault cannot be repaired other than substituting the whole rotating unit I suppose.
But even finding the new substitute parts
this is a very weak point of the rotor model.
Final suggestion : get a stronger unit for your antennas and keep this one for tests or small systems
and\or be prepared to reopen it ! 
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In march'09 I have received also a note from Ken G3MSW :
Dear OM, I found your repair stuff on your web site, and it was helpful.
It seemed to me that the critical part was the spiral which did not slip round because it was glued up a bit with oil.
I cleaned and replaced it after using a ptfe lubricant. I then found that it would not work when assembled and it seemed to a matter of the spring washer on top of the motor drive gear.
If this is too close, it stops, ease it up the shaft and it works, but I wish I knew why. 73 Ken
Following this note , Ken has written a pdf document to report his work on the rotor.
This document is downloadable at mod.dk
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gen.mag. 2007 , gen.09