Hey Jacky,
yeah that clicking is really annoying!  Not all of them do it, about 1 in 4.
The good news is it can be fixed. 
 Remove and/or replace the cap C1. It is the one that the loop switch connects to. On the drawing above, follow the wire from the left lug of the loop switch. This wire connects to C1. Removing it will get rid of the click but I vaguely remember it causing some other problem. In any case replacing it should do the trick. I think it's just a bad cap.