Parkinson Cowan L55GX2WN top oven seal replacement

Brand: Parkinson Cowan
Model Number: L55GX2WN

The top oven seal has hardened and part of it has come away - so the heat is escaping and making the controls quite hot

I have ordered a replacement seal today - BUT looking at the cooker seal - its not obvious how this is removed / replaced

it appears to be locked in-between some metal plates and I'm hoping this does not involve dismantling the top oven

Anyone know how to replace this seal please

etaf, November 2014