More than likely the connections under the seats for the seatbelt tensioners.
Sometimes you can just get away with unplugging and plugging back in a couple of times. MAKE SURE you haven't turned the ignition on for a while to allow for any capacitors to discharge to prevent accidental triggering of the pretentioners.
Failing that, some people hard wire them instead and do away with the plug/socket connectors.
See here for more info (Different car, but same problems.):-
By the time i've dug down to the approximate search area i'll have filled 2 wheely bins and possibly fought off some form of mutant insect monster, the stickers will have been consumed by rabid arthropods ages ago..;)
Bet you find a part used book of Christmas postage stamps though. Usually self adhesive, should be the very thing. The back light from the warning lamp would give it the gravitas of a little stained glass window. Could be quite attractive in a slightly eclesiastical sort of way.