[ChuckS]

Reread thru this series of posts again and since you stated you reversed polarity when reconnecting batteries how long did you sit AFTER this before trying to operate slides?

With the converter not charging those batteries and since the motor turns to take up slack in cables but won’t move slide I’m wondering if your batteries just don’t have the amperage available to move that slide because they are discharged due to non operating converter...

Let us know what you find... for me if the converter chicken bad I’d try connecting battery charger and charge this batteries a few hours and try slid again..

You don’t need a functional converter to operate the slide, just fully charged batteries and then you can troubleshoot the converter..this whole process to test converter is less than a 5 minute process with a meter.