My C-Dales ride straight as an arrow as does my 84 Fuji.
I recently picked up a 84 Lotus and discovered it pulled left if I was at all loose on the bars. I started paying attention to the front wheel's orientation to the down tube while riding in a straight line after making sure the rear wheel was centered. The front wheel was turned slightly left to make the bike go down the road in a straight line. Sighting down the wheels I could visually see that the were not in line with the front wheel lined up with the down tube. The bike was dog legging. The rear wheel even though it was aligned in the triangle was pointing left.

I did something ugly to fix it and only recommend to those that are brave.

With the wheels still on the bike to keep the drop outs spaced I set up blocks of wood under the rear axle, seat post and stem. I then put my weight on the center of the crank to push the bike back into alignment and repeated till the wheels sighted straight. It also will now stay straight when riding hands free.