They may be rusted in place. That seems to be a fairly common occurrence, particularly if you live in a climate where salt is used on the roads. If so, a thorough soaking with WD-40 would probably help.

95 Contour Zetec, ATX (wrecked, sitting in the barn) 95 Mystique Zetec, MTX 2000 Taurus SEL 3.0L Duratec 1994 Crown Victoria LX 4.6 V8 1993 Chevy Silverado 4.3 V6