The hydraulic pump apparently didn't want to run when in the air.  At least
  I got no yellow "running" lamp.  It had run on retraction less than 15
  minutes previously.  The alternate extension got the mains down, but not the
  nose (at least not locked).  I tried cycling the switch several times to no
  avail.  The weather was coming back in, so I didn't have a lot of time to
  play around.
 
  This evening I dropped by the hangar, flipped the battery switch on and the
  hydraulic pump ran constantly, as if the alternate extension bypass were
  open.  It wasn't.  It will be several weeks before I get quality time on the
  airplane, since I have some traveling to do.  I'll let the list know what I
  find.

Naf,

 

1.  Did you get a blip from the pump (down pressure restoration) when you first turned the master switch on?

 

2. Have you recently done things requiring you to pull the pump breaker but not the relay breaker while working on the plane with the master switch on?

 

3. What is the result of testing the down relay operation (i.e. is it stuck in the open position)? 

 

4. The light is powered from the relay contactor. Is the light bulb burned out?

 

5.  Your note that one check had the pump constantly running (what direction?) but the dump valve was closed - puzzling.  Did the light come on?

 

Verrrry Interrrrresting!

 

Side Note:

Just a few days ago I installed a new gas spring in the nose gear because the old one was down to maybe 20 lbs of force.  I also had noticed that recently the nose gear did not instantly lock (lock first) upon lowering the gear on approach. This is the 3rd one since the first flight, over an operational period of 9 years, 680 flight hours and 800 cycles.  I replaced the canopy struts since they were weak too.