are we talking like a continuous wobble or just a quick shake?
Do the Celsiors use a steering rack or recirculating ball steering?
My crown uses recirc ball and i have a continuous wobble problem which starts when i run one wheel over a bump with the steering centred. I have so far isolated the problem down to wheel bearings (replaced), a little play in the steering box and a worn idler arm. Further testing and replacement will help eliminate the rest.
I would start by jacking the front of the car up and get your mate to hold the steering wheel. grab the tyre at the top and bottom and jiggle it - if it has movement then you are looking at wheel bearings.
Now jiggle the wheel left and right - if you ahve movement there its something to do with steering components, and unless you are relatively skilled i would leave that to a professional.