Are you using the tether between engines? I had an issue with mine binding between the engines on 0-36 track...I repositioned the tethers more centered between the doors/diaphrams and the problem was solved.
If it's not the wiring tethers, then I'd ask you to stop the engines on that problem spot and take a look at the couplers...are they bound up at max side travel? I heard these were rated down to 0-31...not sure if the coupler swing will take 0-27 curves.
Anyone wish to chime in who's ran these on 0-27?