Won't start

It only happens every once in awhile. turn the key, all the lights come on, push the start button, nothing. I do hear and feel a click underneath the side cover on the left. I had my dad look at it (much smarter than me with bikes), but he found nothing wrong. Any thoughts?
Thanks!

Check your wiring between your battery, solenoid, and starter. Check your ground wire from your battery to your engine. It sounds like a starter is going south to me. If it were a car Id say when it happens give the starter a whack, ut you cant with the cover on the starter over your bike.

I just had this problem on my '82 440 LTD. It ended up being the starter. I checked and rechecked all the wiring, battery charge, and even tried a little tapping. When i got the starter off, i took it apart and the inside just pretty much fell out. It was full of grit and grime and what not, my main problem ended up being the wires from the brushes were burnt up and half gone. Im guessing this was because it was a 24 year old part. You might want to think about at least taking it off and checking it out, its a very easy process and in fact i did mine on my back porch in about 30 min. or so. Good luck.