quick starting question

I have a 1981 750 LTD that won't start.

What am I forgetting to check? My situation is as follows:

- starter is known to be good
- battery is known to be good
- when starting button is pressed, solenoid makes loud click and sometimes a weak, wheezing effort can be heard from the starter.
- sometimes, but rarely, the bike starts just fine.
- I am able to run along, pop the clutch, and start it right up.

Any thoughts would be greatly appreciated.

Thanks.
JQ

try arcing a large screwdriver across the two terminals on the solenoid if that works then the contactors in the solenoid need to be repaired or cleaned. it might be easier to replace the solenoid but i have rebuilt a few