My external direction indicator lights always work but the dashboard light and click sounder only some of the time. What is the likely cause and why, when I loosen the two screws holding the switch arm in place, does it not want to come out? Is it likely to be a fault with the relay and if so where is it? Thanks in anticipation.

 

From what I have read regarding this situation is that it can be one of three things. The hazard switch, the turn signal lever, or the ignition switch. Next time it is acting up, depress the hazard switch. If it doesn't work, it is likely the culprit. If it is okay, it might be the signal lever. Sound like you tried to get it out already. Besides the two screws, there are a set of pins going into a connector that is hard to see. You will need to pull the unit straight out (toward the driver's door). If jiggling the key in the ignition somehow fixes the problem, then the ignition will need replacing.

source 1: another issue re: turn signals
source 2: similar issue