Patient: doctor it hurts when I do *this*
Doctor: don't do *that*
Seriously, you can't fault a design when you are tugging in places it was not meant to be tugged and has no bearing on how it performs the intended purpose. If you plan to carry around your tripod and camera by the Q3T knob, then I think you ought to find another ballhead.
Well, I just mentioned picking it up by the knob because that's how I first noticed it. You can make it happen just by using it the normal way. I'll just put it this way, since markins is comparable to a "L" lens in the ballhead world, if I were to have a "L" lens where the zoom ring had front to back play of 1-2mm and also had some play before the zoom engaged this would not be acceptable especially when the competition has no play in either direction as the bh-55 doesn't exhibit this. I just wanted to bring it up so others like myself will know what to expect. I've always heard that markins and rrs were the best you can buy in both function and quality. I agree for the most part but the markins falls short slightly due to the play. They are both great companies that make great products and in the case of the 1541T, the markins fit the best so that's why I chose it over rrs.
Don't worry about it. There is both back & forth "looseness" and a very slight of lateral play in the ball locking knob. Markins reassured me about the back and forth looseness, and at least one other person here got in touch with them about the 1mm or so lateral play and was told that it is normal, I read the post in this thread fairly recently. So your ballhead is OK...
peter_n, thank you for putting me at ease about my ballhead. I'm glad it's not defective even though I would have liked no play at all. Anyway, the q3t is still an excellent ballhead and I can't wait to go out and use it in the field.