1988 5KSQ New Owner Questions ("Bomb", Headlights, OXS Warning Light)

["Christopher J. Ritchie" <cjr1@gte.net>]

Been going through this car and the "Bentley", repairing and sorting out
some items.  Queries:

1.  The brake pressure accumulator ("bomb") is getting weak.  How long
before it fails?  When it fails, does it fail catastrophically?  That is,
will there be any warning, or just no brakes one day?  Will it fail while
braking?  Or, could it fail while driving, and I wouldn't know until I
applied the brakes?  Even if it failed completely, shouldn't there still be
some brake pressure assist if the engine is still running?

2.  One of the headlights has water vapor condensed on the inside of the
lens.  The other one has a slight crack.  Are these conditions  harmful? 
Output seems OK.  Is it fixable, or do the headlights need replacing?  If
replacing, isn't there an upgrade?  The headlights are Hellas.  They appear
to be OEM.

3.  My oxygen sensor warning light does not come on when the ignition is
first switched on.  I note that the owner's manual indicates (with an *)
that this is an optional item.  Optional???  Before I go taking the
instrument panel out to check the bulb and tracing the circuit, can someone
tell me if a warning light is supposed to be there.  

4.  What is the faint humming noise near the glove compartment when the
ignition is on?  It is not the fuel pump.  I know that sound and location. 


5.  The "Bentley" does not seem contain scheduled service and regular
maintenance recommendations.  At least I couldn't find them.  Where are
these specified?

6.  I found a listing of the Technical Service Bulletins (TSBs) for this
model.  Where can I find the full text?  If anyone has seen them, are they
something worth obtaining?

Stay tuned as I continue to go through this car.  I am coming to respect
and admire it more and more.