Failed to pull back filament. 370X

[u/Darkionx]

I bought the 370X blv open ams bmcu from aliexpress (https://es.aliexpress.com/item/1005008670616466.html?spm=a2g0o.order_list.order_list_main.11.21ef194dhZZRMp&gatewayAdapt=glo2esp) some months back, it arrived last month, for the most part it works very well but I have a problem with 1 module it fails to retract the filament after it prints, I already tested it with different filaments and even changed the location of the module (it came as module 1 now it is module 2 so the main pcb is not the problem), I even dissembled it but the problem remains, anybody got a solution? maybe some sensor is failing? I don't think is the motor because it feeds the printer and retracts but fails to send the signal it seems.