I guess since slight racket deformation is expected, this naturally implies that the supports and/or arms move a bit whilst stringing. I have noticed that when pulling with my B-150 that the arms might slightly tilt and the frame is slightly pulled towards the dropweight. I noticed this when pulling crosses at 27lbs.
How much movement is expected and at what kind of tensions?
I felt I had to really tighten the 6/12 supports to keep the racket from squashing and now I notice a fair amount of arm/racket movement when pulling. I'm not sure how to gauge what a safe tension to pull is.
I am particularly interested in the behaviour of similarly priced machines e.g. challenger I/II etc.
... as discussed
i suppose you mean the side support arm that holds the side support.
there will be some movement. that's just the way it is. for those who are concern with the racket shape, just add a pound more to the cross tension and watch the tightness of the side support when u finish the stringjob, it should be tight but not loose.
my machine is similar to challenger I but without the fixed clamps. what i did is to measure the frame dimension after i finished the mains (2 pieces method) to determine how much extra pounds applied to the crosses to compensate deformation caused by support movements. typically, gaps will occur at the side supports when doing the crosses and i just keep tightening the side supports to eliminate any gaps on my way.