I find no breaks/cracks in the main line.

How do you remove it for closer inspection. The vacuum pump ends make since it unscrews (metal line portion)

What about the other end?

Is the white distribution plastic thing the check valve that has been mentioned as a possible culprit? This white one is located up by the master cylinder and; after the distribution of many little vaccum send offs, it has a short big line that goes to the Master cylinder

thanks for all the help thus far.

any parts I need.... and a mighty vac are either a 3 hour walk to my house and 3 hour back or a 20 min walk to nappa and 20min back. I have some metric sockets here that's it.

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"If anyone knows other lessons I need to learn, please tell me. I'm tired of learning them the hard way".
by JerryBro

The Glow Plug Wait: This waiting period is a moment of silence to pay honor to Rudolph Diesel. The longer you own your diesel the more honor you will give him". by SD Blue

My normal daily life; either SNAFUed- Situation Normal... All Fouled Up, or FUBARed- Fouled Up Beyond All Repair

62 UNIMOG Camper w/617 Turbo, 85 300SD daily driver- both powered by blended UCO fuels