Hiya all , will be grateful for any assistance given

issue is , my tailgate will lock / unlock with no issues
but i have the electric open struts, which are not working,
i have unhooked from tailgate & body and tested but they do not move.
tried on internal button / external button / key Button , all the same
i went to a breakers yard, and got a pair of replacements, same issue
is there a fuse for these ? i cannot find listed in Handbook
but find it strange that i have 4 that do not move
could it be Module ? but the lock unlock element works ok ?

TIA
keith