Can I ask what you replaced the wheelsets with? I invested in the full highland set and rolling performance is terrible, neither the Revolution CS 92 or the Dapol CS 67 can pull more than 3-4 coaches without ginormous wheelslip.
I've also damaged my yaw dampeners, but mostly through taking the coaches out of the boxes and putting them back in. The plastic covering and the white plastic seating presses down on them and bends them easilly.