Got a few things done on the Columbia yesterday, and thought I'd post some notes.
Steering bearings: There was a lot of play (clunk-clunk) in the steering on this bike, so I dug into it. First thing I noticed, is that this bike is built pretty cheesy. The top triple tree is unusual - the tops of the forks are not directly tied to the steering tube & bearings. There is an intermediate plate, secured by 4 bolts (plus the steering tube top nut), that ties it all together and also serves as the handlebar clamp.
Once apart, it was clear that the bearing set is typical bicycle stuff. Set of races driven into the frame tube, caged bearings, lower cone (a piece of pressed metal, cheapo) driven onto the bottom of the steering tube. The top cone is also the adjuster, with a large knurled outer ring.
The top race had lost it's fit in the tube, and lifted right out. Same for the lower cone - it slipped right off of the steering tube. Cleaned everthing, inspected, packed with grease and reassembled. Replaced the top race, reused the bearings and both cones. Lower cone should have been replaced (it's banged up) but I had no spare, and I punted.
In the end, it seems to have worked fine - way better than when I started. Adjustment of the bearings was very finicky due to the damaged lower cone. About 3 degrees of rotation on the adjuster was the difference between too sloppy vs. binding up.
Two notes on re-assembly and adjustment: When reinstalling the intertmediate plate, tighten down the rear bolts first (evenly). This will bring the plate into contact with the upper cone/adjuster. Then, evenly tighten the front bolts. If you don't do it in this order, you will be left with a gap between the plate and adjuster, and tightening the top nut will either warp the plate, or strip the nut/tube.
Problem is, this also locks the adjuster in place. So, when making final adjustments, you must slack off the rear bolts, move the adjuster, and re-tighten. I had to do this several times before adjustment was correct. On the bright side, once it's adjusted, you can just tighten the top nut, and it has no additional effect on the adjustment (as it normally would).
Last but not least, this bike is built in the fashion of a Harley, Polaris, AMF etc - for every bolt or screw you remove, there is a nut and a washer that falls off of the back. The only place I found captive nuts, was for the 4 bolts that secure the intermediate plate. Pretty cheap.