Strung on a MS200T No Prob
I used to play with a O3 Blue and strung the racket sucessfully w/o a brake or leaning against the wall. The only issues were on the crosses. When I strung the crosses I let the string bend across the open grommet then clamp it. On the next cross I would release that clamp under tension then clamp on the opposite side. I wold repeat this process for all of th crosses. It is a little hard to explain, but was able to do about 20 string jobs during the 2 years I played with the rackets and the string jobs were fine.