REHEARSALS for Hong Kong Ballet's revolutionary epic La Fille Mal Gardee are well under way, but the people in the props department are in a bit of a spin. They have managed to get hold of a set of soldiers' uniforms (flown in from the US), as well as a pair of old-fashioned milk churns (lent by Kowloon Dairy). But they still have a little problem: no spinning wheel. Assistant stage manager Pieta Callender told us that the ballet includes a long set piece about the crusty old mother telling La Fille that she has to spin and cannot go out to dance. ''Without a spinning wheel on stage it's hard to understand what that part of the performance is all about - but these things seem to be a bit thin on the ground in Hong Kong.'' If anyone has such an item sitting in their wardrobe and is willing to lend it to the company for the month of August, then Pieta (tel: 836 0688) would be happy to send a pair of tickets to the show. La Fille Mal Gardee has been choreographed by Heinz Spoerli, and will be performed between August 5 and 20 throughout the New Territories.