Only Half the Loop Runs...

Most likely bad track joints. when the train stops,jump across them with a wire.

Dale H

you should have another power drop at the other end of the loop[farthest from the transformer at the minimum. As Dale H stated your issue is probably bad track joints and having another power line on the other side will help.

Thanks!  I tightened the joints with a pair of pliers and it did the trick.

Aaron

It a good idea put a feeder wire in. I had the same problem with my lionel fastrack a couple weeks ago. Come find out one of the outside pins on my  insulated track with my lionel fastrack railroad crossing signal was broken part way had a bad connection finally broke off competely. Make sure u check your pins are not broken 

I like to run a power feed every 8-10 feet of track.  I am running PW O Gauge track and have approximately 50 feet on the layout and that solved my voltage problem.

spaceghost