I have some vacumm questions I need help on. This is for an 89 Syncro. I'm getting vacumm at the locking diff but it is minimal. The vacumm at the intake on engine is much stronger. Should the vacumm at the locking diff be as strong as at the intake? Secondly, the vacumm line goes from the intake  to some sort of valve on the right side of the engine compartment. From there there is a small line going back to the engine and a larger line going through the firewall but I can't tell where it goes from there. Also the small line going back to the engine has no vacumm on it, what is this for? I've looked at the Bentley manual but can't find anything on vacumm except the diff lock and it's not very in depth (page 34.24). The reason I need to know is the actuator isn't engaging the lock. Everything is working good, the rod isn't stuck and moves in and out easy. The actuator works fine. So I reason there is a leak somewhere but I need to know where to look for it. The vacumm at the reservoir is the same as at the locking diff. Dito fot the lines a=in the dash. Any help or even pointing me to the right pages in the Bentley would be greatly appreciated.

Chip