Brake booster test

[dom14]

Hi guys,
I just did a brake booster test on my RB30 GQ Patrol.

I used the test procedure from Haynes repair manual.
I attached the procedure as a PDF file here.

Here are the results.
If I follow the numbers as in the Brake Booster Check in the document.

21)With the engine stopped, depress the brake pedal several times
The travel distance should not change
Travel distance does change.. Travel distance decreases on each pedal depress. After around 5 presses or so, the brake pedal gets really hard and doesn't go down much. This happened when I did the test in different times(day)
The car was left alone over night or all day before I did this part of the test

22)With the brake fully depressed, start the engine- the pedal should move down a little
when the engine starts.
Yes, test performed as above.

23)Depress the brake, stop the engine and hold the pedal in for about 30 seconds -
the pedal should neither sink nor rise.
Yes the test performed as above

24)Restart the engine, run it for about a minute and turn it off. Then firmly depress the brake
several times - the pedal travel should decrease with each application.
Yes. the test performed as above.

So, other than the very first part of the test( No 21), the test performed ok.

How do I interpret this test result, guys?
Do I have a brake booster or vacuum line issue(either intermittent or permanent)?

Thanks in advance for any assistance.