Rubber изоляционная the plug (it is specified by an arrow) is established in some contact plugs of tips at factory the manufacturer. When you carry electroconducting out repairs, rubber изоляционную the plug is necessary for turning before again inserting into the tip case.
PERFORMANCE ORDER
1) get and cut off the old contact plug 1
2) remove from a wire rubber изоляционную the plug and turn it (on 180 °)
3) examine and replace the plug if it is damaged The prevention
In case of replacement the new plug should be the same colour, as well as old, it will allow to provide necessary tightness between a wire, the plug and the tip case.
4) put on the plug a wire so that the corbel (it is specified by an arrow) was from outside the contact plug 1