Front Hub Vacuum Route ?

I think that I have a blockage somewhere in the front hub vacuum system,,not the pipes,,and wondered if anyone has a detailed diagram of the exact route of the locking and unlocking passageways so that I can clean things out. If I has access to an airline I would just blast them through but alas its hand tools only. Any ideas ?

I don't know if this is as detailed as you want.

Do you have a push-button transfer?

Thanks for that,,its a far better image than I have seen so far but it still just shows the pipes disappearing behind that hub plate. I'm wanting to see the exact passageway that each vacuum pipe takes through the hub/mechanism to lock and unlock it. It may seem a bit pedantic but I know what it does and now I want to know how it does it ! Thanks again. PS. its a push button system.

I would love to help as I suspect the normal solution to just switch to manual hubs is at best a bit hasty. The vacuum hubs have a bad reputation but very seldom I see someone like you who wants to fix them.
I love my vacuum hubs. Had manual on my previous cars and I often did forget to switch them over..
It is like the SJ413 carb that everyone says to replace, but it is serviceable..
Have you had a look in the FSM for the hubs?

The reason I wanted to know if it was a push button transfer is so that I could ask a follow-on question.

Someone can correct me if I am wrong but I believe if there is a blockage in the lines to the hubs, your hubs wouldn't engage but the transfer would engage successfully (the controller would still see a vacuum). When you push the 4WD button does the transfer engage or do you have flashing lights? I'm thinking that if you have flashing dash lights, you more likely have a vacuum leak.

Once you press the 4xd button, the transfer box engages the drive shaft to the front wheels and the vacuum hubs engage the wheels to the drive shaft. You can have a situation whereby the hubs do not engage or only one engages and the dash light will show you in 4xd. The way I check is to take off the hubs and see which has engaged. Its also worth carrying a hex socket and wrench for that purpose to get you out of trouble.
Flashing lights can indicate a transfer box problem; there’s a couple of solenoid switches on the transfer box where the wires get pulled out as happened to me or a problem with the vacuum.
If you go over to manual hubs then you block the pipes to make the system function so having blockage will have the same effect ie no flashing lights.
These are my experiences of the system which can be very frustrating however there are chaps on here who are far more experienced than me who should be able to put you right.
Good luck
bryn