for anyone who read my last thread “rear coupler mystery” I think I have solved it. in a reply by iguanaman3 he mentoined that electrical spikes could trigger the rear coupler. as the problem would only happen while pulling my K-line streamliners I focused on them. I found one of the roller springs let loose and the roller was bouncing along. on these cars the axle is right above the roller so when it bounced up and hit the axle Viola, a spike. I repaired the spring and so far all is good. thanks for the input Neil.[:)][:D][^]