speed bag problems
This sounds like you are describing a free standing floor bag stand that has a single vertical pole up the middle with a speed bag rebound board attached. There are several models of these available and it is my experience that NONE of them are stable enough to allow a decent speed bag workout. Even without seeing your unit, I doubt that this problem is related to the speed bag bladder. The problem is, that board is most like a thin, 24 inch presswood particle board with no stabilization weight or straps attached to hold it steady and offer resistance to the pounding of the bag mulberry purse on it. The board probably gives tremendously as the bag hits, killing the rebound. Co mulberry purse uple that with the single vertical pole and the unit probably sways and twists at the pole as you punch, further killing the rebound.
The only help I can offer is to try and put about 25 30 pounds of resistance over the top of the board ( be sure th mulberry purse is does not “tip” the unit). Many people use bags of sand or concrete mix over the top to cover the board. This will help stabilize the board but probably not stop the vertical pole from swaying and twisting. The is no simple fix for that. I would also suggest getting a smaller bag, such as an 8×5 or 7×4. These take more speed bag skill to control, and if they are a bit too fast for you I suggest you take a bit of air out of them to make it a bit “flat”. It won’t rebound as well but it will slow it down a bit if it’s hard to keep up. Also, don’t punch hard, which will add more vibration to the board and pole, slowing it down more than speeding it up.
I’m not sure this will really fi mulberry purse x the problem because all present models of free standing floor frames that I have any experience with have exactly the same problem. I hope you can get to the point of having a more stable wall unit at some time in the future.