Although it may not be EXACTLY what you need, it's a good start. I believe the 'adjustment screw' is on the 'face' of the window frame, itself; NOT in the jam. (Although I could be wrong.) Look for adjustment screws. They could be of the Phillips type or Allen Wrench type or who knows. If you know the brand, attempt to contact a dealer or the Mfgr. Perhaps someone else can give a better 'picture' of what it looks like. I'm pretty sure of what I'm saying - Just not 100%.
My best to ya and hope this helps.
Jay J -Moderator
PS: Obviously, depending on the 'type' of screw, that's going to dictate the tool ... (You'll need to know the different between a Phillips, Allen, and/or Flat screw. (Well, it would probably help ...)