C:31:20 Take-up reel side tape slacking when unloading.
C:32:20 " "
C:31:21
Supply reel side tape slacking when unloading..
C:32:21 " "
C:31:22 Take-up reel fault
C:32:22 " "
C:31:23 Supply reel fault
C:32:23 " "

Generally a mechanical fault. The reel tables and/ or idler are suspect, as well as the mechanics surrounding them. It's also possible that the reel sensor themselves are at fault. Intermediate to major labor.