Mark Petry had some questions. Here are the answers:
1- Does the QR feel smooth as it takes up the slack ? Yes. Although there is more friction in the rear one as compared to the front one.
2- Is the 7mm nut tight? Absolutely 3- Is it possible that the QR was re-assembled incorrectly, for example, the cable fixing bolt is on the inside, not the outside? No. It is assembled correctly.
Mark's suggestion to dis-assemble and re-grease eveything made me think that grease might not be the way to go. I did dis-assemble, but did not re-grease to see if I could increase the friction and solve the problem. Thre result is that the front QR still has less friction than the front.
What do you think of using carbopaste or some other form of friction-increasing compound?