I downloaded "Divertimento I" from the Robert C. Walshe's website to be played by the Alt-Aumund Blockflöten-Ensemble in August, 2010. This appears to be the same piece as Serenade 1 (From K 439b)
, much edited by the removal of phrasing The bass part is usefully written in the bass clef thus avoiding the mental gymnastics required of less experienced bass players. The sheet music for free downloading comprises a
and the above midi.
Very many thanks Mr Walshe!