Re: Ibanez ProLine PR1550 Truss Rod Adjustment
Hm, I don't know if these ever came with a special wrench... I think you have to take off the string lock to adjust the truss rod, yeah, PITA... My RS525 had this arrangement and with the lock in place, I could never get the wrench in there. I converted the guitar to hardtail and ditched the lock for a Floyd type string retainer, which allows for simple adjustment.
Unless you get a wrench that has a short tip (or cut one down to size), I don't see any other way of doing it besides taking off the lock.