vauxhall corsa window slider clip on regulator?

my window dropped towards bonnet and after takin g door panel off realised its the white plastic slider that sits in side the runner had snapped so the metal arm was not connected right..

have bought the new plastic clip which comes with the rivet already in it ...

question is how to attached it to the metal arm as the metal arm as got the old rivet attached to it

so what i thought was an easy job of putting clip in runner and pushing the arm to clip into it has gone out the window lol

any ideas how to get the old rivet out the arm and attach the arm to the new rivet which is inserted in the new clip???????????

help????

corsa 1.4 auto n reg -- manual windows

NICKI
May 2010