UK Car Repair: s type indicator fault, offside indicator, emery paper

Question
my offside indicator is only producing a weak flash. I tred replacing the bulb and tried out a new rear lamp unit but the problem persists. The offside rear reversing lamp will not work and the nearside reversing lamp tries to flash with the indicator. It doesn't do this when I disconnect the offside lamp cluster. Any ideas? Thankyou

Answer
Before anything else...

Take out EVERY bulb from BOTH clusters and clean the contacts (and metal body) of each bulb and its holder with emery paper - then lightly dab the contacts with grease before refitting.

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If there's still a problem after this.. there wont be a problem after this :)