The dome light assembly is mounted in a cutout in the headliner using four (longish) plastic legs: one very fragile straight leg on each side near the front (grips at end facing out) and two slightly less fragile curved (U-shaped) legs along the back side (grips at end facing rear). For removal, pull the front straight down. It may seem to take some effort. Absolutely avoid twisting or turning the unit to avoid breaking the retaining legs. Then slide the unit slightly forward so you can pull the whole thing down.

Make note of the wiring when you disconnect the terminals even though the tabs are normally stamped with the wire color (not always easy to see).

I'm not sure if there's a particular light you're having a problem with or all of them (as you seem to suggest). If pushing the unit up makes everything work then the problem is likely a loose or broken wire. If you're talking about being able to push up one of the front map light switches (a common problem) then that will almost certainly be a broken switch retainer strap which can often be repaired using epoxy (not the metal kind) to secure the strap on its posts. If you break a leg, they can be successfully glued back in place using epoxy (plastic cement is useless) in a small mound to support the base of the leg in the groove.

FYI, the wiring is as follows (should be common to all 900's and 700's):

black: chassis ground
green/red: +12V through fuse 5 from battery
brown/black: chassis ground through opened front/rear door switches (A-pillar)
white/black: chassis ground through opened front door switches (B-pillar)
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Dave -940's, prev 740/240/140/120 You'd think I'd have learned by now