2.6 - Replace the o-ring

Remove the old rubber o-ring seal from the upper edge of the chassis and ensure that the recess in which it was sitting is clean.

Wearing protective latex (or equivalent) gloves, coat a new o-ring seal with a thin layer of silicone grease and place it into the recess.
IMPORTANT: Take care not to get any grease onto the lens/dish reflector assembly when fitting the o-ring seal. If it does, carefully remove immediately with a soft dry cloth.