Worn, discolored gasket

Removed old gasket fairly easily after removing wire and spring retainers on front and back surface. New gasket went into place relatively easily, but re-installing rear retainer was extremely difficult without special tools. Improvised a spring stretcher using steel wire looped through the eyelets in the ends of the retainer and back on itself to get leverage, still very difficult and took several tries. Front retainer went on easily.