[A/S] Shower Faucet

["jarrodjwhite" <jjwhite@xxxxxxxxxxxx>]

I'm slowly and steadly making progess on my 65 Ambassador.  I finally 
got it entirely replumbed (using Pex piping) and got the leaks 
stopped (I replaced the threaded plastic joints with brass fittings 
and cooper crimp rings using a rented crimper).  I fixed the leaky 
washers on the bathroom lavatory faucet and kitchen sink with 
success.  Now, all that is left is the shower faucet.  I replaced the 
broken flex tube and turned it on with great fanfare, only to 
discover that water is spraying out the backside of the faucet in the 
middle part between the hot and cold knobs.  I can't figure out how 
to disassemble the faucet to take a look at the leak to either fix or 
replace.
  My Ambassador has the integrated sink and tub/shower.  The plastic 
extends under the sink all the way to the wall.  The only idea I had 
about getting to the faucet was to drill out all the rivits 
connecting the bottom part of the sink assembly to the top, remove 
the sink faucet (I'm not quite sure how either), and unscrew the sink 
drain to lift the top off. Surely, there is an easier way. Please 
help?
 Also, assuming I get past this crisis - any ideas on how to improve 
the appearance of my faded and stained sink and tub/shower.  Can I 
paint it? And, I need help figuring out how the shower curtin works - 
since mine was missing.
 Thanks in advance.
Jarrod