I have seen this happen when the upper control arm bolts could not put enough squeeze on the frame ears. The new Moog bolts at that time did not have enough threading on them to affect a squeeze. I Torqued the bolt and thought it was tight, but all I had done was run the nut to the bottom of the threads. It put enough squeeze on, on the rack, but the first time I hit the brakes in reverse,backing off the rack, I heard this "clunk". Getting out, I saw that the UCA on one side had slipped and slammed to the front of the opening. It was a do-over for me. After I figured it out, the solution was hardened washers under the bolt head and nut. And yes, I did both sides.This gave ne about 3/16 to 1/4 inch more thread to make a good clamp with.
I was working by the hour, but the alignment rate was fixed to the customer. So; the customer got the benefit, my boss lost an hour, and I got the education. I was able to do the job right,cuz I was not being driven by the clock.
Check your UCA; I bet it's moving. You deserve to get that corrected and a free realignment. You didn't screw up. You shouldn't have to pay for the tech's education.
