Perentie brake problem

[buckmaster07631]

After my Perentie was sitting for a bit...it developed a brake issue...very hard to press brake pedal with limited resultant braking.  After some discussion the assumption was the brake booster had failed.  I had the booster rebuilt and the problem has not resolved.  Also my diff lock light came on...could it be a problem with the vacuum system?
I am in the USA and my only experience with Perentie's is the one that I own...so any and all advice is appreciated.

[BEARMAN]

G'day buckmaster. Try disconnecting the brake vacuum hose from the nipple on the booster and see if there is suction there. If there is vacuum there the problem will be in something else like the master cylinder. If there is no vacuum check the rubber hoses and the lines themselves that go to the vacuum pump on the alternator and the diff lock switch in the cabin. Then take the hose off the alternator pump and see if there is vacuum there. The 6x6 has a vacuum reservoir under the rh guard just above the headlight. Sometimes a steel line can crack or a hose perish. The diff lock light is a bit of a mystery as it requires vacuum to operate and the switch needs to be pulled out to activate it. Have a listen for hissing noises around the dash where the switch is mounted. It is possible that the switch may be malfunctioning.

[buckmaster07631]

Thank you Bearman...I will try this weekend and report back.

[buckmaster07631]

Problem seems to be the vacuum pump on back of alternator...the one part of the system that in theory is the least likely to fail.  Not sure if I can just find that part so I am sourcing a cheap alternator with pump.