I have run Novaks for more than 30 years starting with the T1 and all the way through the GTB, XBR, and Havoc. I have had one Dually fail. There service is excellent. It sounds to me like there were issues prior to your getting them and after limited use they failed. The seller may not have known but buying second hand electronics is a gamble at any time.

I have run a few Tekins but went back to Novak. Never had issues with Tekin just liked my Novaks better. At this time I have nine different vehicles with them installed. Two old Duallys, one GTX, two XRSs, two XBRS, Two Havocs, and a GTB.