Posted for "Paul Nafziger" <naf@britevalley.com>:

 That's a real possibility.  Tonight I turned the battery switch on again and
 moved the valve on and off.  The tone of the pumped changed like the
 pressure was lower with the valve in the alternate gear extension position.
 That would tend to back your theory.  I need to get the engine off and torn
 apart, the prop to a prop shop, and then I'll start troubleshooting.