<VV> Air Compressor Help (Off Topic)

[John]

I've got a two stage air compressor that has failed and I need some
help.  The unit will not hold pressure because there is a leak at the
bleed hole between the first stage piston output and the second stage
input.  The leak is at the hole in a brass elbow located in line with
the crankshaft.  One end of the elbow connects directly into the
casting.  The other end connect via a 1/4 copper tubing to the larger
piston head.  Disassembly shows the the elbow contains a small needle
value much like a tire valve stem.  It's actuated by a rod that is in
line with the crankshaft.  The rod is attached to a flywheel centrifugal
governor that's part of the crank shaft.  The needle valve will hold air
when you blow through it and will pass air when you depress the needle. 
I don't know for sure but I assume the centrifugal governor assembly is
intended to release the pressure on the the head for motor re-starts.  I
have not yet removed the air pump head.  Can anyone tell me if my
problem is likely with the needle valve or with the valves in the head? 
What's likely wrong if anything in the head?  I assume the head contains
some kind of reed valve but I don't really know since I've never taken
an air pump apart.  Do reed valves get stuck or do they completly fail? 
The operation of the air compressor has changed somewhat prior to it's
failure.  Normally when the air compressor would reach its set high
pressure it would belch out a fart, releasing pressure via the described
needle valve.  The compressor now runs much longer and when it does
reach the high end set pressure there is a continuous leak.  Any
suggestions would be appreciated.

John "airless" Dozsa