Built Platform Stuck

Have a problem with my build platform. Anyone have suggestions or guides how do I fix this please? Model is UP! MINI 2. Thanks

Video available at the FB group or from my Google Drive



I would think the idle pulley is broke; ref https://www.thingiverse.com/thing:3461323

I did get a replacement part after a couple of weeks of back and forth with Tiertime, thingiverse part kept it limping along while waiting until the belt failed completely.