a/c not blowing thru front dash vent on 2002 Cadillac DeVille DTS

a/c blows thru defrost & floor vents, not thru front vents

Asked by for the 2002 Cadillac DeVille DTS
Had this prob on my 02 Caddy Deville (base); there is a solonoid that switches a door back and forthe to direct air flow. In thier wisdom, GM uses plastic gears for this function, so either the solonoid is bad and is not switching, or the gears are stripped and the 'door' is not moving. Either way, it's a dealer only part for about $125 or so. You'll need a contortionist to get up under the dash to replace it for you.
What is a contortionist?and can I fix it my self,,?