Hi Smugger, Recently had to change my passenger side mirror indicator due a another errent stone on the motorway smashing the lens
...it is a sealed led unit with 3 leds, cost is £45.10. It is possible that water from cleaning the car has got is also and got into the block connector mine had and the connectors pins were green instead of copper!!! getting to them can be a bit of a lottery, it is simple but if done wrong you can also break the mirror cover
which i was informed by the dealer.....decided to do it myself and was a 5 minute job.... first used a plastic knife to prise the underneath of the mirror cover off and then slowly work your way round the mirror to loosen it....then simply pull the whole cover forwards with a bit of 'jiggling' to help!! but please be careful as if too heavy handed the cover clips can break and this will result in a new cover being required also
. LED unit is secured with 3 hex screws. Easy job to be honest but most dealers will probably do the fitting for free if a new unit required. Hope this helps and good luck