DrJohn:

It is almost certainly a marginal fuse. Check the archives, "fuse" " JCE" there are about 18 threads there on this topic. If I recall when it happened to me it was a white fuse , #5? that looked perfect but fell into 2 parts when removed. The clicking is the rapid switching of current on and off to the instroments. If it gets bad enough, it will sound like a buzzer.

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John

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