This is what I did but keep in mind I had to restart the game from the beginning. Going
back abit like to 60% or 50% just was not working.
First off after the training mode, that is after I delivered the tape to the preacher to
get my pills. I started by Working for the APR, getting my missions only from them and
from all my buddy's and a few from weapons dealers in order to unlock more weapons. Until
I had no choice but to take a job from the other faction.(UFLL) Also I never took a
mission from any cell tower.
There are maps available on the net to show you where all the tapes and diamonds are in
both the north section and south section. I gathered all the tapes on the way as I went on
my missions. When it finally came time to go and meet Rubin at the marina bar I had all
the tapes(16 in all 8 in the north & 8 in the south)in my possession, and the door open
just as it should. But sometime before that, I had also gone to the marina bar to take a
mission from one of my buddies.
I completed the game,and I'm now playing it for the third time. Great game and a surprise
at the end but I'm not going to spoil it for you. Have fun!