lawnmower drive not working

Hi

my mower Briggs & Stratton engine bottom of lawnmower do not know the make it has none .

anyway my drive cable snapped weeks ago . it broke at the handle end and i did a temp fix to connect to the handle . last week the drive to the rear wheels stopped . i stripped the rear wheels transmission etc out disconnected the drive cable. while removing the rear section a broken spring fell out and i have no idea where it has come from . the broken spring is obviously my problem but where has it come from .

would the spring be around the drive cable end / as ive seen on cables online.
or would the spring be used to keep tension on the transmission ?


any help appreciated
can upload pics if need be