On our 580 Super M, the large nut on the end of the pin where the dipper (stick) pins to the boom backed off while I was backfilling some ditch saturday. How tight should it be tightened. I've heard of over-tightening breaking the cast boom. What about some locktite on it? When we bought the machine, it had a regular stick on it when we looked at it, and the dealer swapped out an extendahoe stick on it, so it's been apart since it left the factory. We've put about 1800 hours on it before this happened.
If the nut has not come off, all you should need to do is tighten it. There maybe shims behind the large washer, these set the amount of crush when the nut is tightened, so unless this is tampered with no amount of tightening will break the boom. Pic is from the manual. :drinkup