Before you purchase another sewing machine, do you have a 1/4 inch foot with guide?It makes my piecing so easy and accurate. Another thing that might help, I bought a seam ruler with marks for a scant 1/4 inch, a full 1/4 inch, and other marks so that the sewer can have exactly the size seam that they want. I bought the seam ruler on e-bay. Another thing I found very helpful for cutting is June Tailor's Shape Cut Rulers. I cut perfect strips. Do you engage the built in walking foot when piecing? I, too, have a Pfaff and a Bernina and a couple of Brothers. I have the 1/4 inch foot with guide for ALL my sewing machines. Have you had your sewing machine checked over recently? Before spending thousands on a new sewing machine, I would take it in and make sure that nothing is wrong with it. If nothing is wrong with the machine, then getting a new sewing machine probably won't help.It's how you are either cutting or pressing the blocks. Make a simple 9 patch and then measure the block.If it isn't measuring correctly, it is possible that instead of making a 1/4 inch seam, perhaps you are sewing a 1/2 inch seam. As far as a sewing machine improve your accuracy, I think you are going to have to check your seams as you go along making the block. I think you will find out pretty fast what you are doing wrong. Good luck!