Might just be a relay . If your lucky you may be able to swap over the up relay for the down and see if the fault follows the relay . You could also use a volt meter to see if both relays are working.
There is only one trim motor that spins one way for up and tother way for down ...ergo , if the motor goes down it must be ok and the fault is most likely an up relay . The relays decide the polarity of the current flow supplied to the trim motor to give you up or down .
