I recently picked up a pair of Atlas Centuries, C628 and C630, used from a train show. The C628 is a noisy runner, squealing a lot, but still dependable. The 630 is another matter. Right off, it could barely pull itself along; it would lurch forward, then almost stop, crawl for a bit, then lurch again. I checked the forum and dismantled the engine. It eventually became apparent that the problem was a loose male universal, which would occasionally spin out. After trying a few remedies, I dabbed a bit of superglue on there to keep it in place. Now the problem has changed. If I put it on the track, the lights will come on, but the engine won’t move. Instead it will just hum. Add enough power and it will slowly move (enough to show the previous problem was fixed), but very slowly. I’m guessing somewhere in all that assembly/dissasembly, something fouled up, but I can’t figure out what. Any suggestions? On a side note, the trucks on these seem to like to fall apart. It’s happened three times, although not in a week or so. Is this a common problem with these engines?
Doesn't that just make it more prototypical? Maybe I'm wrong, but it seems to me they mostly had electrical problems. I guess GE saved all the most special components for them. Most likely the glue created a situation where some moving part is too tight, creating resistance to movement. Does the drive shaft and universal now shove the worm hard up against a bushing? How about the motor armature? By the way, what size are these things? HO? N?
If the unit remains stationary and hums until you add enough throttle, I agree with acptulsa that something is binding in the mechanism. There needs to be some play in the driveline. As you lay the components in place be sure that they'll be able to move a bit along their length. With the trucks removed, lightly roll them and be sure that they aren't binding from a piece of ballast in the gears or whatever. I'd also remove the motor and bench test it for smoothness. Members here recently helped me get my used (Atlas N Scale) SD-35 running, but I had electrical pickup troubles that you aren't experiencing.
When you reassemble the locomotive, make sure the motor mount tabs are engaging properly with the holes in the frame. I've noticed the motor mount cradles in Atlas and Kato engines are flexy and don't always want to snap into place. I had a similar binding issue in a Life-Like C-Liner that I traced to the motor mounts being out of alignment. However, that loco uses ring mounts for the motor, not a cradle like the C630. Check that the bearing blocks for the worm gears are also seated properly and not in a diagonal position. They won't cause binding themselves, but they can possibly prevent the frame halves from closing fully when you screw them together. The C628/C630 chassis is NOT a "Beardenization" candidate, so leave all the worm gear bearing blocks in place.
I decided to temporarily remove the forward worm/shaft, and see what happened. The result was a smooth running engine. Then I disassembled it again and looked at the universal/armature. It looks like that dab of superglue splurted out a bit and solidified, thus preventing the shaft from fully attaching. I used a small knife and screwdriver to clean most of it out. I don’t think it’s all out, but now my engine can run around my steep and curvy layout just fine, and more quietly than it’s C628 counterpart. I may try and get a bit more gunk out when I add the decoder again.
