Ray,
Regarding your question about the NPP K-2, I suppose you have discovered a fact
which has disappointed a lot of other people -- while they look very good, many
of those locomotives do not run well just out-of-the-box. This used to be a
pretty common problem with a great many brass steam locomotives.
It may well be that you have the time, ability and resources to troubleshoot
the problem, pinpoint exactly where the binding is occurring, and fix it as it
should be fixed. I admire that and hope you are successful.
However, if you'll be satisfied with a quick fix I can tell you what I have
seen work for others in the past.
Lay the locomotive upside-down in a foam rubber cavity narrow enough to support
the sides. Remove the bottom cover plate completely. Attach electrical leads
away from the running gear and turn up the juice until the flaw in the motion
is well-defined. With a toothpick in each hand, lightly depress the journals
for the drivers. One side, then the other, sometimes both (one a little more
than the other, probably). When depressing, if the motion smoothes out note the
particular driver and journal, and the approximate distance of the depression.
Thereafter, apply shims of that thickness between the journal and the bottom of
the cover plate, when reattaching the latter.
I have seen this technique work well for many modelers struggling with jerky
mechanisms in older brass steam locomotives. It smoothes out the motion and
does not compromise the tracking qualities of the drivers. Oftentimes the shim
is so small that when the locomotive is back on the rails one cannot even tell
that that driver has been lifted slightly. Sometimes though, it is more
pronounced. But I have never seen one so pronounced as to be objectionable in
appearance. The general consensus of opinion is that HO scale brass steam
locomotives look a whole lot better when they run well.
Of course, this quick fix is not always effective and it may not work in your
particular case. But I have seen the technique employed to good effect in the
past and so I thought it was worth passing along to you for whatever help it
might give. Good Luck!
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