How-To replace oven rim's rubber gasket -- need guidance!!!

[Rollingstone06]

My electric oven rim's gasket has torn off on several parts after 8 years of use. It's a Scandinavian oven -- Helkama, model number G 6745 (60 cm). I've now removed the oven door, and bolts at the back of the oven interior space, but still don't have full enough access to get all the crumbling parts of the old gasket out. Question is, should the oven interior plate slide out fully for access (I can't see how, maybe you know?), or is it a matter of getting leverage at several points of that rim with some flat objects stuck in there to gain access? And should that new gasket be pushed in bit by bit, or should it be put in place in one go? (I really wanna get rid of any traces of that old gasket.)

Hope you can offer some guidance to this DIYer -- will be much appreciated!

Cheers,
RS