I believe that is a floating caliper so some play would be normal. If you have too much your caliper body may be worn and or the pins it slides on may be worn. Hitting the wheel weights may not be the best measure since they could be put in the wrong place on the wheel. I'd start by looking at the pins it all slides on since they may be cheaper and easier to change than the caliper itself.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.