My buddy has a 97 F150 4x4 and the front differential was not locking in. we diagnosed the problem as a stuck solenoid on the front differential. A little WD 40 and it was operating properly. Anyone experienced this problem before?

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99 SC 4X4 5.4 ORP 3.73LS Lariat Black over Gold on Tan.
Mods-Powerdyne Supercharged,Superchip,Dual Flowmasters,Westin Nerf Bars, 305/70/16 GY M/T's, Extang Black Max Tonneau