I added a locator to our FR10 sleeve-transfer trial and the original tray behaved better, then a replacement tray brought another missed pickup; posting the limitation alongside the improvement because our handover currently calls the locator fix complete, and it isn't.
Put each tray's identity and the observed result beside the change. Our training notes became clearer when we recorded what was actually tried rather than naming a modification as a fix. Have you compared the replacement tray's pockets from its locating feature?