I've found some more info on the indicator switch that plays up. In addition to this problem I have also recently experienced that lights go out when changing from hi to lo beam. I figure this is closely realted to the switch issue as I beleive there are some contcts located just below the switch that is the hi low beam swicth that plays up. My plan is just change the whole unit over but I beleive there is an indicator switch rebuild kit available for the 240, not sure about the 260. I've copied much of the thread below, also a link to the original thread for those that might experince the same problem in future, (note all pic's shown on the original thread), a pic of the dodgy switch below:
http://www.classiczcars.com/forums/showthread.php?t=9944&highlight=indicator+switch