Re: Need a bit of help with my JEM555
The only way to tell if the truss rod needs adjustment is to check neck relief. If the bridge is too low, just raise the studs on either side until the action is high enough that the strings are not buzzing. Then you'll be able to get your feeler gauges out to measure the neck relief. If the neck has back-bow, loosen the truss rod. If there is too much forward bow, tighten the truss rod. If it does need adjustment, you'll need a 7mm socket that should have come with the guitar when new, not an Allen wrench.
At this stage of the game, if raising the bridge doesn't solve your problem, take your guitar to a trusted tech. While you're there, ask him to show you how to properly make simple adjustments so that your Jem will always be in top form.