Hi Guys,  This is my first time responding to a post. I've been quietly reading the forums here for sometime now saying nothing, but now I feel the need to put in my fifty cents. I just recieved my k27 464 a few days ago.  As with most of you guys I was really impressed.  Speachless to say the least. WOW !!!  However, I was a little disappointed when I began running the engine to find some binding in the running gear, but kind of expected it to have a few glitches considering it is a new product.  I took the top styrofoam shipping container that the engine came in to use as a cradle to support the engine upside down.  First thing I noticed was alot of wobble in the counterweights. They were loose, really loose, all eight of them.  Like most of you guys the first thing I tried to do was tighten the counterweight screws only to find them all tight.  Being somewhat mechanically minded, I decided to take the counterweights apart to inspect. With the counterweight off the axle I removed the screw and washers from the center of the counterweight and placed the counterweight back onto the axle.  Upon inspection of the fit between the axle and the counterweight I noticed alot a excessive play between the two.  There is a flat area machined about a quarter way through the axle that mates up with a flat area molded into one side of the counterweight axle hole.  I could twist the counterweight about 1/8 turn in each direction.  Way too much slack in my opinion.  I cut some small brass shims about 1/8" squares to insert in between the two on the flat area to take up the slack.  I had some .005" and .002" brass sheet stock on hand.  The magic thickness for all eight counterweights was .007". With the engine upside down in the cradle I put the small brass shims onto the flat area of the axle ( flat area turned up) held in place with a small screwdriver and pushed the counterweight back onto the axle.  The result was very little or no twisting slack.  With the screw reinserted and tight, the counterweight still appeared to be loose as far as there was some in and out slack ( not twisting ) on the axle.  It looks as if the screw bottoms out on the axle before the screw and washer tighten against the counterweight.  I removed the counterweights and lightly made a couple strokes across each axle end with a file. I probably didn't even remove a .001" from each axle end.  With all counterweights reinstalled brass shims and all,  the axle counterweight joints became rock solid.  Upon fixing the loose counterweight problem it appeared to fix my other problem of the running gear ( siderods ) binding up.  In my opinion the loose counterweights twisting, and all becoming out of quarter, directly contributed to the binding and jerky motion of the engine while running.   When all was done with the engine and put back into service on the rails, it ran like a dream.  I hope that this might be of help to someone.  I was happy with the engine to begin with and even happier now.    Thanks guys, Bill