AMAs seem to be the cool thing to do lately, so thought I'd give it a try. Have been a mechanic for 15 odd years, worked on everything from Hyundai to Porsche. Recently moved to marine in the last year or so. Will try to answer when I can.
Edit - Wow this was much more popular than anticipated, thanks for the great response everyone, hopefully it's helped a few people out.
Have you (or anyone you know at your workplace) ever told someone naïve that something needs replacement when in fact, it didn't?