Technobeam-i motors

I have a bunch of Technobeam-i's that see very little use (maybe 10-20 hours / year). In 2012, I replaced the color wheel, litho, pan, tilt, and focus motors on one fixture. Getting them ready for an upcoming gig and I find that the Pan, litho, & color wheel motors are all frozen again. I've heard there were motor issues when these were manufactured, and almost all motors on the fixtures have been replaced. (All my TB-i's have very low hours and most were purchased new.) I'd be tempted to think the replacement motors were NOS from the 'bad' era, but not from the reputable source I get my parts from. I have many other High end fixtures with some seeing the same very low number of annual hours, and motors in those have never been an issue. Is a low duty cycle for TB motors just as bad as 1000's of hours in terms of motor longevity / reliability ? I'd hate to replace them again just to find them frozen again in a few years. Did I get another batch of bad motors? Or do I need to exercise the fixtures regularly to keep the motors working?
Thanks!
- Mike
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