How to replace/install rubber door seal on domestic Tecnik electric cooker?

I have completed a major clean of a Tecnik domestic electric cooker. I have removed the rubber door seal to prevent damage by caustic cleaning materials. I now come to refit the door seal, but am finding it difficult to get the seal to fit into the slot to be able to feed it right around the door opening. Is there a 'method' to doing this please?
Many thanks.