That problem, leading edge flaps hanging is common to various Boeing models. Funny thing, in the Douglas DC-8, a similar problem exists with the trailing edge flaps, if planes are parked for awhile, without hydraulic pressure. It is not uncommon to see the trailing flaps "sagging" down and aft, some "10, 20 or more" as position. However, the DC-8 has no "leading edge devices" like Boeings have. The problem with Kruger flaps in i.e. the Boeing 727, is that "little birds" are keen to build well protected nests in these areas.
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So you might get an omelet when you power the hydraulic systems...
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Happy contrails